Terminal device, base station device, and communication method

ABSTRACT

A terminal device (UE) includes a reception unit configured to monitor multiple enhanced physical downlink control channels (EPDCCHs) on a Secondary cell. In a case that the Secondary cell is a licensed assisted access Secondary cell and a higher layer parameter of the Secondary cell indicates that a starting position of downlink transmission is either a Subframe boundary or a slot boundary, the terminal device is configured to monitor both a first set of UE-specific search space candidates in a first EPDCCH and a second set of UE-specific search space candidates in a second EPDCCH, in a subframe. A starting symbol for the first EPDCCH is specified by an index in a first slot in the subframe. A starting symbol for the second EPDCCH is specified by the index in a second slot in the subframe.

TECHNICAL FIELD

Embodiments of the present invention relate to a technique of a terminaldevice, a base station device, and a communication method that achieveefficient communication.

BACKGROUND ART

The 3rd Generation Partnership Project (3GPP), which is astandardization project, standardized the Evolved Universal TerrestrialRadio Access (hereinafter referred to as the “E-UTRA”), in whichhigh-speed communication is realized by adopting an OrthogonalFrequency-Division Multiplexing (OFDM) communication scheme and flexiblescheduling using a unit of prescribed frequency and time called resourceblock.

Moreover, the 3GPP discusses the Advanced E-UTRA, which realizeshigher-speed data transmission and has upper compatibility with theE-UTRA. The E-UTRA relates to a communication system based on a networkin which base station devices have substantially the same cellconfiguration (cell size); however, regarding the Advanced E-UTRA,discussion is made on a communication system based on a network(different-type radio network, Heterogeneous Network) in which basestation devices (cells) having different configurations coexist in thesame area. The E-UTRA is also referred to as the “Long Term Evolution(LTE)”, and the Advanced E-UTRA is also referred to as the“LTE-Advanced”. The LTE may be a general term including theLTE-Advanced.

A carrier aggregation (CA) technique and a dual connectivity (DC)technique are defined, in which, in a communication system where cells(macro cells) having large cell radii and cells (small cells) havingsmaller cell radii than those of the macro cells coexist as in aheterogeneous network, a terminal device performs communication byconnecting to a macro cell and a small cell at the same time (NPL 1).

On the other hand, discussion is made on Licensed-Assisted Access (LAA)in NPL 2. In the LAA, an Unlicensed spectrum used in a wireless LocalArea Network (LAN) is used as the LTE, for example. Specifically, theUnlicensed spectrum is configured as a Secondary cell (secondarycomponent carrier). The Secondary cell used as the LAA is assistedregarding connection, communication, and/or configuration by a Primarycell (primary component carrier) configured in a Licensed spectrum. TheLAA extends a spectrum available to the LTE, allowing broadbandtransmission. The LAA is also used in a shared spectrum which is sharedbetween predetermined operators.

Moreover, latency in radio communication is one of critical factors in asystem aiming at ensuring security and reliability. For the LTEsincluding the LTE using the LAA and the LTE of the related art using aLicensed spectrum, it is important to further reduce latency.

CITATION LIST Non Patent Literature

-   NPL 1: 3rd Generation Partnership Project; Technical Specification    Group Radio Access Network; Evolved Universal Terrestrial Radio    Access (E-UTRA); Physical layer procedures (Release 12), 3GPP TS    36.213 V12.4.0 (2014-12).-   NPL 2: RP-141664, Ericsson, Qualcomm, Huawei, Alcatel-Lucent, “Study    on Licensed-Assisted Access using LTE”, 3GPP TSG RAN Meeting #65,    September 2014.

SUMMARY OF INVENTION Technical Problem

In the LAA, in a case that an Unlicensed spectrum or a shared spectrumis used, the spectrum is shared with another system and/or anotheroperator. However, the LTE is designed on the assumption of being usedin a Licensed spectrum or a non-shared spectrum. Therefore, the LTE ofthe related art cannot be used in the Unlicensed spectrum or the sharedspectrum. In addition, reduction in latency in radio communication isdesired for the LTEs including the LTE using the LAA and the LTE of therelated art using a Licensed spectrum.

The present invention has been made in light of the foregoing, and anobject of the present invention is to provide a terminal device, a basestation device, and a communication method that enable efficient controlof a cell that uses a Licensed spectrum, an Unlicensed spectrum, or ashared spectrum.

Solution to Problem

A terminal device according to an aspect of the present invention is aterminal device (UE) including a reception unit configured to monitormultiple enhanced physical downlink control channels (EPDCCHs) on aSecondary cell. In a case that the Secondary cell is a licensed assistedaccess Secondary cell and a higher layer parameter of the Secondary cellindicates that a starting position of downlink transmission is either aSubframe boundary or a slot boundary, the terminal device is configuredto monitor both a first set of UE-specific search space candidates in afirst EPDCCH and a second set of UE-specific search space candidates ina second EPDCCH, in a subframe. A starting symbol for the first EPDCCHis specified by an index in a first slot in the subframe. A startingsymbol for the second EPDCCH is specified by the index in a second slotin the subframe.

A base station device according to an aspect of the present invention isa base station device configured to communicate with a terminal device(UE). The base station device includes a transmission unit configured totransmit multiple enhanced physical downlink control channels (EPDCCHs)on a Secondary cell. In a case that the Secondary cell is a licensedassisted access Secondary cell and a higher layer parameter of theSecondary cell indicates that a starting position of downlinktransmission is either a Subframe boundary or a slot boundary, theterminal device is configured to monitor both a first set of UE-specificsearch space candidates in a first EPDCCH and a second set of theUE-specific search space candidates in a second EPDCCH, in a subframe. Astarting symbol for the first EPDCCH is specified by an index in a firstslot in the subframe. A starting symbol for the second EPDCCH isspecified by the index in a second slot in the subframe.

A communication method of a terminal device according to an aspect ofthe present invention is a communication method of a terminal device(UE). The communication method includes the step of monitoring, by theterminal device, multiple enhanced physical downlink control channels(EPDCCHs) on a Secondary cell. In a case that the Secondary cell is alicensed assisted access Secondary cell and a higher layer parameter ofthe Secondary cell indicates that a starting position of downlinktransmission is either a Subframe boundary or a slot boundary, theterminal device is configured to monitor both a first set of UE-specificsearch space candidates in a first EPDCCH and a second set of theUE-specific search space candidates in a second EPDCCH, in a subframe. Astarting symbol for the first EPDCCH is specified by an index in a firstslot in the subframe. A starting symbol for the second EPDCCH isspecified by the index in a second slot in the subframe.

A method of a base station device according to an aspect of the presentinvention is a communication method of a base station device configuredto communicate with a terminal device (UE). The communication methodincludes the step of transmitting, by the base station device, multipleenhanced physical downlink control channels (EPDCCHs) on a Secondarycell. In a case that the Secondary cell is a licensed assisted accessSecondary cell and a higher layer parameter of the Secondary cellindicates that a starting position of downlink transmission is either aSubframe boundary or a slot boundary, the terminal device is configuredto monitor both a first set of UE-specific search space candidates in afirst EPDCCH and a second set of the UE-specific search space candidatesin a second EPDCCH, in a subframe. A starting symbol for the firstEPDCCH is specified by an index in a first slot in the subframe. Astarting symbol for the second EPDCCH is specified by the index in asecond slot in the subframe.

Advantageous Effects of Invention

The present invention can provide improved transmission efficiency in aradio communication system in which a base station device and a terminaldevice communicate.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating an example of a downlink radio frameconfiguration according to the present embodiment.

FIG. 2 is a diagram illustrating an example of an uplink radio frameconfiguration according to the present embodiment.

FIG. 3 is a schematic diagram illustrating an example of a blockconfiguration of a base station device 2 according to the presentembodiment.

FIG. 4 is a schematic diagram illustrating an example of a blockconfiguration of a terminal device 1 according to the presentembodiment.

FIG. 5 is a diagram illustrating an example of a communication procedurein a LAA cell according to the present embodiment.

FIG. 6 is a diagram illustrating an example of the communicationprocedure in the LAA cell according to the present embodiment.

FIG. 7 is a diagram illustrating an example of the communicationprocedure in the LAA cell according to the present embodiment.

FIG. 8 illustrates an example of an EREG configuration in one RB pair.

FIGS. 9A to 9E are diagrams illustrating examples of a configuration ofDMRSs associated with a second EPDCCH to be used for a first partialsubframe.

FIGS. 10A to 10E are diagrams illustrating examples of a configurationof DMRSs associated with a second EPDCCH to be used for a second partialsubframe.

DESCRIPTION OF EMBODIMENTS First Embodiment

A first embodiment of the present invention will be described below.Description will be given by using a communication system (cellularsystem) in which a base station device (base station, NodeB, or eNodeB(eNB)) and a terminal device (terminal, mobile station, user device, orUser equipment (UE)) communicate in a cell.

Note that, in the description of the present embodiment, the descriptionof downlink covers downlink in a normal cell and downlink in a LAA cell.For example, the description of a downlink subframe includes a downlinksubframe in a normal cell, a full subframe in a LAA cell, and a partialsubframe in a LAA cell.

Main physical channels and physical signals used in EUTRA and AdvancedEUTRA will be described. The channel refers to a medium used to transmita signal, and the physical channel refers to a physical medium used totransmit a signal. In the present embodiment, the physical channel maybe used as a synonym of signal. In the future EUTRA and Advanced EUTRA,the physical channel may be added or its constitution and format typemay be changed or added; however, the description of the presentembodiment will not be affected even in a case where the channel ischanged or added.

In EUTRA and Advanced EUTRA, scheduling of a physical channel or aphysical signal is managed by using a radio frame. A single radio frameis 10 ms in length, and a single radio frame is constituted of 10subframes. In addition, a single subframe is constituted of two slots(i.e., one subframe is 1 ms in length, and a single slot is 0.5 ms inlength). Moreover, scheduling is managed by using a resource block as aminimum unit of scheduling for allocating a physical channel. Theresource block is defined by a certain frequency domain constituted of aset of multiple subcarriers (e.g., 12 subcarriers) on a frequency axisand a domain constituted of a certain transmission time period (a singleslot).

FIG. 1 is a diagram illustrating an example of a downlink radio frameconfiguration according to the present embodiment. The downlink uses anOFDM access scheme. In the downlink, a PDCCH, an EPDCCH, a PhysicalDownlink Shared CHannel (PDSCH), and the like are allocated. A downlinkradio frame is constituted by a downlink Resource Block (RB) pair. Thisdownlink RB pair is a unit for allocation of a downlink radio resourceand the like and is based on the frequency band of a predefined width(RB bandwidth) and a time duration (two slots=1 subframe). Each of thedownlink RB pairs is constituted of two downlink RBs (RB bandwidth×slot)that are contiguous in the time domain. Each of the downlink RBs isconstituted of 12 subcarriers in the frequency domain. In the timedomain, the downlink RB is constituted of seven OFDM symbols in a casethat a normal cyclic prefix is added, while the downlink RB isconstituted of six OFDM symbols in a case that a cyclic prefix that islonger than the normal cyclic prefix is added. A domain defined by asingle subcarrier in the frequency domain and a single OFDM symbol inthe time domain is referred to as a “Resource Element (RE)”. A PhysicalDownlink Control Channel is a physical channel on which downlink controlinformation such as a terminal device identifier, Physical DownlinkShared Channel scheduling information, Physical Uplink Shared Channelscheduling information, and a modulation scheme, coding rate, andretransmission parameter are transmitted. Note that, although a downlinksubframe in a single Component Carrier (CC) is described here, adownlink subframe is defined for each CC and downlink subframes areapproximately synchronized between the CCs.

Although not illustrated here, Synchronization Signals, a PhysicalBroadcast Information Channel, and a downlink Reference Signal (RS) maybe assigned, to a downlink subframe. Examples of a downlink ReferenceSignal include a Cell-specific Reference Signal (CRS: Cell-specific RS),which is transmitted through the same transmission port as that for aPDCCH, a Channel State Information Reference Signal (CSI-RS), which isused to measure Channel State Information (CSI), a terminal-specificReference Signal (URS: UE-specific RS), which is transmitted through thesame transmission port as that of one or some PDSCHs, and a DemodulationReference Signal (DMRS: Demodulation RS), which is transmitted throughthe same transmission port as that for an EPDCCH. Moreover, carriers onwhich no CRS is assigned may be used. In this case, a signal (referredto as an “enhanced Synchronization Signal”) similar to a signalcorresponding to one or some transmission ports (e.g., only transmissionport 0) or all the transmission ports for the CRSs can be inserted intoone or some subframes (e.g., the first and sixth subframes in the radioframe) as time and/or frequency tracking signals. The terminal-specificReference Signal transmitted through the same transmission port as thatof one or some PDSCHs is also referred to as a “terminal-specificReference Signal associated with a PDSCH” or a “DMRS”. The DemodulationReference Signal transmitted through the same transmission port as thatof the EPDCCH is also referred to as a “DMRS associated with an EPDCCH”.

Although not illustrated here, a Discovery Signal (DS) may be assignedto the downlink subframe. For the terminal, a Discovery signalsmeasurement timing configuration (DMTC) is set up (configured) based ona parameter configured via RRC signaling. A DMTC Occasion is 6 ms inlength and is constituted of six contiguous subframes. Moreover, theterminal presumes that no DS is transmitted in any subframes outside theDMTC Occasion.

In a cell, the DS (DS Occasion) is constituted of a time period (DSperiod) of a prescribed number of contiguous subframes. The prescribednumber is 1 to 5 in FDD (Frame structure type 1), and 2 to 5 in TDD(Frame structure type 2). The prescribed number is configured by RRCsignaling. The DS period or its configuration is also referred to as a“Discovery signals measurement timing configuration (DMTC)”. Theterminal presumes that the DS is transmitted (mapped, generated) foreach subframe configured by a parameter dmtc-Periodicity configured byRRC signaling. The terminal presumes that the DS configured to includethe following signals exists in the downlink subframe.

(1) An CRS on an antenna port 0 within a DwPTS of all the downlinksubframes and all special subframes in the DS period.

(2) A PSS in the first subframe in the DS period in FDD. A PSS in thesecond subframe in the DS period in TDD.

(3) An SSS in the first subframe in the DS period.

(4) A non-zero-power CSI-RS in zero or more subframe in the DS period.The non-zero-power CSI-RS is configured by RRS signaling.

The terminal performs measurement based on the configured DS. Themeasurement is performed by using the CRS in the DS or thenon-zero-power CSI-RS in the DS. In the configuration concerning the DS,multiple non-zero-power CSI-RSs can be configured.

The DS and DMTC in the LAA cell can be the same as a DS and DMTC in FDD.For example, in the LAA cell, the DS period is any of 1 to 5 as in FDD,and the PSS exists in the first subframe in the DS period. Note that theDS in the LAA cell may be configured differently from a DS in a normalcell. For example, the DS in the LAA cell does not include any CRS.Moreover, the DS in the LAA cell includes a PSS and SSS that can shiftin the frequency direction.

Moreover, in the LAA cell, a control signal and/or a control channelincluding control information can be transmitted at a subframe in the DSOccasion or a subframe in the DMTC Occasion. The control information caninclude information on the LAA cell. For example, the controlinformation is information on the frequency, the load, the congestiondegree, the interference, the transmit power, the channel occupationtime, and/or the buffer state relating to transmission data, in the LAAcell.

Moreover, the control signal and/or the control channel can bedemodulated or detected through the DMRS in the DS Occasion. In otherwords, the control signal and/or the control channel is transmitted viaan antenna port used for DMRS transmission in the DS Occasion.Specifically, the DMRS in the DS Occasion is a Demodulation ReferenceSignal (DMRS) associated with the control signal and/or the controlchannel and can be configured similarly to the DMRS associated with thePDSCH or the EPDCCH.

Moreover, the scramble sequence used for the DMRS associated with thecontrol signal and/or the control channel may be generated differentlyfrom the scramble sequence used for the DMRS associated with the PDSCHor the EPDCCH. Here, the scramble sequence used for the DMRS isgenerated with a value calculated based on the slot number (subframenumber), the first parameter, and the second parameter, which are usedas initial values. For example, in the scramble sequence used for theDMRS associated with the PDSCH, the first parameter is a Cell Identifier(Cell ID) or a value configured by a higher layer, and the secondparameter is 0 or 1 given by the DCI. In a case that the secondparameter is not given by the DCI, the second parameter is fixed at 0.In the scramble sequence used for the DMRS associated with the EPDCCH,the first parameter is a value configured by a higher layer for eachEPDCCH set, and the second parameter is fixed at 2.

In the scramble sequence used for the DMRS associated with the controlsignal and/or the control channel, the first parameter is a valueconfigured by a higher layer, and is the Cell Identifier of the LAA cellor the Cell Identifier corresponding to the non-zero-power CSI-RS in theDS Occasion. In the scramble sequence used for the DMRS associated withthe control signal and/or the control channel, the second parameter is avalue fixed at a prescribed value or a value configured by a higherlayer. In a case that the second parameter is fixed at the prescribedvalue, the second parameter takes a value of any of 0, 1, and 2 similarto the second parameter used in the scramble sequence used for the DMRSassociated with the PDSCH or the EPDCCH, or a value (for example, 3)different from the second parameter used in the scramble sequence usedfor the DMRS associated with the PDSCH or the EPDCCH. In a case that thesecond parameter is configured by a higher layer, the second parametercan be configured at any value and can be configured, for example, at anoperator-specific value.

Moreover, the control signal and/or the control channel can bedemodulated or detected through use of a CRS in the DS Occasion. Inother words, the control signal and/or the control channel istransmitted via an antenna port used for CRS transmission in the DSOccasion. Note that a scramble sequence used for the CRS in the DSOccasion can be generated based on the first parameter and/or the secondparameter described with respect to the scramble sequence used for theDMRS associated with the control signal and/or the control channel.

FIG. 2 is a diagram illustrating an example of an uplink radio frameconfiguration according to the present embodiment. The uplink uses anSC-FDMA scheme. In the uplink, a Physical Uplink Shared Channel (PUSCH),a PUCCH, and the like are allocated. An uplink Reference Signal isassigned to one or some of PUSCHs and PUCCHs. An uplink radio frame isconstituted of uplink RB pairs. This uplink RB pair is a unit forallocation of uplink radio resources and the like and is constituted bythe frequency band of a predefined width (RB bandwidth) and apredetermined time duration (two slots=1 subframe). A single uplink RBpair is constituted by two uplink RBs (RB bandwidth×slots) that arecontiguous in the time domain. Each of the uplink RBs is constituted of12 subcarriers in the frequency domain. In the time domain, the uplinkRB is constituted of seven SC-FDMA symbols when a normal cyclic prefixis added, while the uplink RB is constituted of six SC-FDMA symbols whena cyclic prefix that is longer than the normal cyclic prefix is added.Note that although an uplink subframe in a single CC is described here,an uplink subframe is defined for each CC.

A Synchronization Signal is constituted by three kinds of primarySynchronization Signals and secondary Synchronization Signalsconstituted by 31 kinds of codes that are interleaved in the frequencydomain. 504 patterns of cell identifiers (Physical Cell Identities;PCIs) for identifying base station devices, and frame timing for radiosynchronization are indicated in combinations with the primarySynchronization Signals and the secondary Synchronization Signals. Theterminal device identifies the Physical Cell ID of a receivedSynchronization Signal by cell search.

A Physical Broadcast Channel (PBCH) is transmitted for the purpose ofannouncing (configuring) a control parameter (broadcast information(System information)) commonly used among the terminal devices withinthe cell. The radio resource in which broadcast information istransmitted is announced on the Physical Downlink Control Channel to theterminal devices in the cell. Broadcast information not announced on thePhysical Broadcast Information Channel is transmitted, as a layer-3message (System information) for announcing the broadcast information onthe Physical Downlink Shared Channel, by the announced radio resource.

As broadcast information, a Cell Global Identifier (CGI), whichindicates a cell-specific identifier, a Tracking Area Identifier (TAI)for managing a standby area in paging, random access configurationinformation (such as a transmission timing timer), shared radio resourceconfiguration information, neighboring cell information, and uplinkaccess control information of the cell, and the like are announced.

A downlink Reference Signal is classified into multiple types accordingto its use. For example, Cell-specific RSs (Cell-specific referencesignals) are pilot signals transmitted with prescribed power from eachcell and are downlink Reference Signals periodically repeated in thefrequency domain and the time domain under a prescribed rule. Theterminal device receives the Cell-specific RS and thereby measures thereception quality of each cell. The terminal device also uses aCell-specific RS as a Reference Signal for demodulation of a PhysicalDownlink Control Channel or a Physical Downlink Shared Channeltransmitted at the same time as a Cell-specific RS. A sequence used fora Cell-specific RS is a sequence distinguishable among the cells.

The downlink Reference Signal is also used for estimation of downlinkchannel variation. A downlink Reference Signal used for estimation ofchannel variations is referred to as a “Channel State InformationReference Signal (CSI-RS)”. A downlink Reference Signal individuallyconfigured for the terminal device is referred to as a “UE-specificReference Signals (URS), a Demodulation Reference Signal (DMRS), or aDedicated RS (DRS)”, and is referred to for a channel compensationprocess for demodulating an Enhanced Physical Downlink Control Channelor a Physical Downlink Shared Channel.

A Physical Downlink Control Channel (PDCCH) is transmitted by using thefirst several OFDM symbols (e.g., 1 to 4 OFDM symbols) of each subframe.The Enhanced Physical Downlink Control Channel (EPDCCH) is a PhysicalDownlink Control Channel allocated to the OFDM symbols to which thePhysical Downlink Shared Channel (PDSCH) is allocated. The PDCCH orEPDCCH is used for notifying each terminal device of radio resourceallocation information according to scheduling determined by the basestation device and information indicating an adjustment amount for anincrease or decrease in transmit power. In the following, even when thePhysical Downlink Control Channel (PDCCH) alone is described, bothphysical channels that is, the PDCCH and the EPDCCH, are included unlessotherwise noted.

The terminal device needs to monitor a Physical Downlink Control Channeladdressed to the terminal device itself, and receive the PhysicalDownlink Control Channel addressed to the terminal device itself, beforetransmitting and receiving downlink data or a layer-2 message or layer-3message, which is higher-layer control information (such as a paging orhandover command), and thereby acquire, from the Physical DownlinkControl Channel, radio resource allocation information called an uplinkgrant in a case of transmission and a downlink grant (downlinkassignment) in a case of reception. Note that it is also possible toconstitute the Physical Downlink Control Channel so that the PhysicalDownlink Control Channel is to be transmitted in the dedicated resourceblock domain allocated to each terminal device by the base stationdevice, instead of transmission through OFDM symbols described above.

The Physical Uplink Control Channel (PUCCH) is used for anacknowledgment in response to reception of downlink data transmitted onthe Physical Downlink Shared Channel (HARQ-ACK; Hybrid Automatic RepeatRequest-Acknowledgment or ACK/NACK; Acknowledgment/NegativeAcknowledgment), downlink channel (channel state) information (CSI:Channel State Information), and uplink radio resource allocation request(radio resource request, Scheduling Request (SR)).

CSI includes a Channel Quality Indicator (CQI), a Precoding MatrixIndicator (PMI), a Precoding Type Indicator (PTI), and a Rank Indication(RI), which can be used respectively for specifying (representing) apreferable modulation scheme and coding rate, a preferable precodingmatrix, a preferable PMI type, and a preferable rank. Indication may beused as a notation for each Indicator. Moreover, the CQI and the PMI areclassified into a wideband CQI and PMI assuming transmission using allthe resource blocks in a single cell and a subband CQI and PMI assumingtransmission using some contiguous resource blocks (subbands) in asingle cell. Moreover, the PMI may be a type of PMI that represents asingle preferable precoding matrix by using two kinds of PMIs, a firstPMI and a second PMI, in addition to a normal type of PMI, whichrepresents a single preferable precoding matrix by using a single PMI.

The Physical Downlink Shared Channel (PDSCH) is also used to notify theterminal device of Broadcast information (System information) that isnot notified by paging or on the physical broadcast information channel,in addition to downlink data, as a layer-3 message. The radio resourceallocation information on the Physical Downlink Shared Channel isindicated by the Physical Downlink Control Channel. The PhysicalDownlink Shared Channel is allocated to OFDM symbols other than the OFDMsymbols used to transmit a Physical Downlink Control Channel and istransmitted. In other words, the Physical Downlink Shared Channel andthe Physical Downlink Control Channel are time division multiplexed in asingle subframe.

The Physical Uplink Shared Channel (PUSCH) mainly transmits uplink dataand uplink control information and may also transmit informationincluding uplink control information such as CSI and ACK/NACK. Moreover,the Physical Uplink Shared Channel is also used by the terminal deviceto notify the base station device of the layer-2 message and layer-3message, which are higher-layer control information, in addition touplink data. The radio resource allocation information on the PhysicalUplink Shared Channel is indicated by the Physical Downlink ControlChannel, as in a case of downlink.

The Uplink Reference Signal (also referred to as an “uplink pilotsignal” or an “uplink pilot channel”) includes a Demodulation ReferenceSignal (DMRS) to be used by the base station device to demodulate thePhysical Uplink Control Channel PUCCH and/or Physical Uplink SharedChannel PUSCH, and a Sounding Reference Signal (SRS) to be mainly usedby the base station device to estimate an uplink channel state.Moreover, the Sounding Reference Signals are categorized into a PeriodicSounding Reference Signal (Periodic SRS), which is transmittedperiodically, or an Aperiodic Sounding Reference Signal (Aperiodic SRS),which is transmitted when transmission is instructed by the base stationdevice.

A Physical Random Access Channel (PRACH) is a channel used to announce(configure) a preamble sequence with a guard time. The preamble sequenceis constituted so that the base station device is notified of theinformation with multiple sequences. For example, when 64 sequences areavailable, 6-bit information can be provided to the base station device.The Physical Random Access Channel is used by the terminal device as ameans for accessing the base station device.

The terminal device uses the Physical Random Access Channel to requestan uplink radio resource when no Physical Uplink Control Channel isconfigured for an SR or to request the base station device fortransmission timing adjustment information (also referred to as a“Timing Advance (TA) command”) necessary for matching uplinktransmission timing to a reception timing window of the base stationdevice, for example. Moreover, the base station device can request theterminal device to start a random access procedure, by using thePhysical Downlink Control Channel.

The layer-3 message is a message exchanged between the RRC (radioresource control) layers of the terminal device and the base stationdevice and handled in a protocol for a Control-plane (C-plane), and maybe used as a synonym of RRC signaling or RRC message. A protocolhandling user data (uplink data and downlink data) is referred to as a“User-plane (UP (U-plane))” in contrast to the “Control-plane”. Here, atransport block which is transmission data in the physical layer,includes C-plane messages and U-plane data in the higher layers.Detailed description of other physical channels is omitted.

A communicable range (communication area) at each frequency controlledby the base station device is assumed to be a cell. Here, thecommunication area covered by the base station device may be differentin size and shape for each frequency. Moreover, the covered area may bedifferent for each frequency. A radio network in which the cellscontrolled by different types of base station devices and havingdifferent cell radii coexist in the area on the same frequency and/ordifferent frequencies to form a single communication system, is referredto as a “heterogeneous network”.

The terminal device operates by assuming the inside of a cell as acommunication area. When the terminal device moves from a cell to adifferent cell, the terminal device moves to an appropriate differentcell through a cell reselection procedure in a case of having no radioconnection (during no communication) and through a handover procedure ina case of having radio connection (during communication). A suitablecell is in general a cell that is determined that access from theterminal device is not prohibited based on information specified by thebase station device and that has a downlink reception quality satisfyinga prescribed condition.

Moreover, the terminal device and the base station device may employ atechnique for aggregating the frequencies (component carriers orfrequency band) of multiple different frequency bands through carrieraggregation and treating the resultant as a single frequency (frequencyband). A component carrier includes an uplink component carriercorresponding to the uplink and a downlink component carriercorresponding to the downlink. In this specification, “frequency” and“frequency band” may be used as synonyms.

For example, when five component carriers each having a frequencybandwidth of 20 MHz are aggregated through carrier aggregation, aterminal device capable of carrier aggregation performs transmission andreception by assuming that the aggregated carriers have a frequencybandwidth of 100 MHz. Note that component carriers to be aggregated mayhave contiguous frequencies or frequencies some or all of which arediscontiguous. For example, assuming that available frequency bands area band of 800 MHz, a band of 2 GHz, and a band of 3.5 GHz, a componentcarrier may be transmitted in a band of 800 MHz, another componentcarrier may be transmitted in a band of 2 GHz, and yet another componentcarrier may be transmitted in a band of 3.5 GHz.

It is also possible to aggregate multiple contiguous or discontiguouscomponent carriers of the same frequency band. The frequency bandwidthof each component carrier may be narrower (e.g., 5 MHz or 10 MHz) thanthe receivable frequency bandwidth (e.g., 20 MHz) of the terminaldevice, and the frequency bandwidths of component carriers to beaggregated may be different from each other. Each frequency bandwidth ispreferably equal to any of the frequency bandwidths of cells of therelated art in consideration of backward compatibility but may be afrequency bandwidth different from any of the frequency bands of cellsof the related art.

Moreover, component carriers (carrier types) without the backwardcompatibility may be aggregated. Note that the number of uplinkcomponent carriers to be allocated to (configured for or added for) theterminal device by the base station device is preferably the same as orfewer than the number of downlink component carriers.

A cell constituted of an uplink component carrier in which an uplinkcontrol channel is configured for a radio resource request and adownlink component carrier having a cell-specific connection with theuplink component carrier is referred to as a “Primary cell (PCell)”. Acell constituted of component carriers other than those of the Primarycell is referred to as a “Secondary cell (SCell)”. The terminal devicereceives a paging message, detects update of the broadcast information,carries out an initial access procedure, configures securityinformation, and the like in a Primary cell, and need not perform theseoperations in Secondary cells.

Although the Primary cell is not a target of Activation and Deactivationcontrols (in other words, considered as being activated at any time),the Secondary cell has activated and deactivated states, the change ofwhich is explicitly specified by the base station device or is madebased on a timer configured for the terminal device for each componentcarrier. The Primary cell and Secondary cell are collectively referredto as a “Serving cell”.

The carrier aggregation is communication using multiple componentcarriers (frequency bands) by multiple cells and is also referred to as“cell aggregation”. The terminal device may have radio connection withthe base station device via a relay station device (or repeater) foreach frequency. In other words, the base station device of the presentembodiment may be replaced with a relay station device.

The base station device manages a cell, which is an area where terminaldevices can communicate with the base station device, for eachfrequency. A single base station device may manage multiple cells. Thecells are classified into multiple types of cells depending on the sizesof the areas (cell size) that allow communication with terminal devices.For example, the cells are classified into macro cells and small cells.Moreover, the small cells are classified into femto cells, pico cells,and nano cells depending on the sizes of the areas. When a terminaldevice can communicate with a certain base station device, the cellconfigured so as to be used for the communication with the terminaldevice is referred to as a “Serving cell” while the other cells not usedfor the communication are referred to as a “Neighboring cell”, among thecells of the base station device.

In other words, in carrier-aggregation (also referred to as “carrieraggregation”), multiple Serving cells thus configured include a singlePrimary cell and one or more Secondary cells.

The Primary cell is a Serving cell in which an initial connectionestablishment procedure has been carried out, a Serving cell in which aconnection re-establishment procedure has been started, or a cellindicated as a Primary cell during a handover procedure. Operation at aprimary frequency is performed in the Primary cell. At the point of timewhen a connection is (re)established, or later, a Secondary cell may beconfigured. Operation at a secondary frequency is performed in eachSecondary cell. The connection may be referred to as an “RRCconnection”. For the terminal device supporting the CA, a single Primarycell and one or more Secondary cells are aggregated.

In the present embodiment, Licensed Assisted Access (LAA) is used. Inthe LAA, a Licensed spectrum is configured (used) for the Primary cell,and an Unlicensed spectrum is configured for at least one of theSecondary cells. The Secondary cell for which the Unlicensed spectrum isconfigured is assisted by the Primary cell or Secondary cell for whichthe Licensed spectrum is configured. For example, configuration and/ornotification of the control information by RRC signaling, MAC signaling,and/or PDCCH signaling is performed from the Primary cell or Secondarycell for which the Licensed spectrum is configured to the Secondary cellfor which the Unlicensed spectrum is configured. In the presentembodiment, the cell assisted by the Primary cell or Secondary cell isalso referred to as an “LAA cell”. The LAA cell can be aggregated with(assisted by) the Primary cell and/or the Secondary cell by the carrieraggregation. The Primary cell or Secondary cell assisting the LAA cellis also referred to as an “assist cell”. In addition, a cell for which aLicensed spectrum is configured is also referred to as a “normal cell”(cell of the related art), and a subframe in the normal cell is alsoreferred to as a normal subframe (subframe of the related art). Thenormal subframe includes a downlink subframe, an uplink subframe, and aspecial subframe. In the present embodiment, description will be givenof the normal subframe as distinguished from the subframe used in theLAA cell.

The LAA cell may be aggregated with (assisted by) the Primary celland/or the Secondary cell through dual connectivity.

A basic configuration (architecture) of the dual connectivity will bedescribed below. A description is given of a case that the terminaldevice 1 connects to multiple base stations 2 (e.g., a base stationdevice 2-1 and a base station device 2-2) at the same time, for example.Assume that the base station device 2-1 is a base station deviceconstituting a macro cell, and the base station device 2-2 is a basestation device constituting a small cell. The terminal device 1connecting to the base station devices 2 at the same time by using themultiple cells belonging to the multiple base station devices 2 asdescribed above is referred to as “dual connectivity”. The cellsbelonging to the respective base station devices 2 may be operated atthe same frequency or different frequencies.

Note that the carrier aggregation is different from the dualconnectivity in that a single one of the base station devices 2 managesmultiple cells and the frequencies of the respective cells are differentfrom each other. In other words, the carrier aggregation is a techniquefor connecting the single terminal device 1 and a single one of the basestation devices 2 via multiple cells having different frequencies, whilethe dual connectivity is a technique for connecting the single terminaldevice 1 and the multiple base station devices 2 via multiple cellshaving the same frequency or different frequencies.

The terminal device 1 and the base station devices 2 can apply atechnique used for the carrier aggregation, to the dual connectivity.For example, the terminal device 1 and the base station devices 2 mayapply a technique of allocation of a Primary cell and Secondary cells orActivation/Deactivation, to the cells connected through the dualconnectivity.

The base station device 2-1 or the base station device 2-2 is connectedto an MME and an SGW via a backbone network. The MME is a host controlstation device corresponding to a Mobility Management Entity (MME) andhas the functions of managing mobility and performing authenticationcontrol (security control) for the terminal device 1, and configuringroutes for the user data to the base station devices 2. The SGW is ahost control station device corresponding to a Serving Gateway (S-GW)and has the functions of transmitting the user data according to theroute for the user data to the terminal device 1 configured by the MME.

Moreover, the connection route between the base station device 2-1 orbase station device 2-2 and the SGW through the dual connectivity isreferred to as an “SGW interface”. The connection route between the basestation device 2-1 or base station device 2-2 and the MME is referred toas an “MME interface”. The connection route between the base stationdevice 2-1 and the base station device 2-2 is referred to as a “basestation interface”. The SGW interface is also referred to as an “S1-Uinterface” in the EUTRA. The MME interface is also referred to as an“S1-MME interface” in the EUTRA. The base station interface is alsoreferred to as an “X2 interface” in the EUTRA.

An example of an architecture for enabling the dual connectivity isdescribed. In the dual connectivity, the base station device 2-1 and theMME are connected via the MME interface. Moreover, the base stationdevice 2-1 and the SGW are connected via the SGW interface. The basestation device 2-1 provides, to the base station device 2-2, thecommunication route to the MME and/or SGW via the base stationinterface. In other words, the base station device 2-2 is connected tothe MME and/or the SGW via the base station device 2-1.

Moreover, another example of another architecture for enabling the dualconnectivity is described. In the dual connectivity, the base stationdevice 2-1 and the MME are connected via the MME interface. The basestation device 2-1 and the SGW are connected via the SGW interface. Thebase station device 2-1 provides, to the base station device 2-2, thecommunication route to the MME via the base station interface. In otherwords, the base station device 2-2 is connected to the MME via the basestation device 2-1. The base station device 2-2 is connected to the SGWvia the SGW interface.

Note that a constitution in which the base station device 2-2 and theMME are directly connected via the MME interface may be employed.

On the basis of description from a different point of view, the dualconnectivity is an operation whereby a prescribed terminal deviceconsumes radio resources provided from at least two different networkpoints (a master base station device (MeNB: Master eNB) and a secondarybase station device (SeNB: Secondary eNB)). In other words, in the dualconnectivity, the terminal device is configured to establish an RRCconnection to at least two network points. In the dual connectivity, theterminal device may be connected via a non-ideal backhaul in an RRCCONNECTED state.

In the dual connectivity, the base station device that is connected toat least the S1-MME and that serves as a mobility anchor of a corenetwork is referred to as a “master base station device”. Moreover, thebase station device that is not the master base station device and thatprovides supplemental radio resources to the terminal device is referredto as a “secondary base station device”. A group of Serving cells thatis associated with the master base station device may be referred to asa “Master Cell Group (MCG)”, and a group of Serving cells that isassociated with the secondary base station device may be referred to asa “Secondary Cell Group (SCG)”. Note that the cell groups may be servingcell groups.

In the dual connectivity, the Primary cell belongs to the MCG. Moreover,in the SCG, the Secondary cell that corresponds to the Primary cell isreferred to as a “Primary Secondary Cell” (pSCell). Note that the pSCellmay be referred to as a “special cell” or a “Special Secondary Cell(Special SCell)”. Some of the functions (e.g., functions fortransmitting and receiving a PUCCH) of the PCell (the base stationdevice constituting the PCell) may be supported by the Special SCell(the base station device constituting the Special SCell). Additionally,only some of the functions of the PCell may be supported in the pSCell.For example, the function for transmitting a PDCCH may be supported inthe pSCell. Additionally, the function for performing a PDCCHtransmission may be supported in the pSCell using a search spacedifferent from a CSS or USS. For example, the search space differentfrom the USS is a search space determined based on a value defined inthe specification, a search space determined based on an RNTI differentfrom the C-RNTI, a search space determined based on a value configuredby the higher layer that is different from the RNTI, or the like.Moreover, the pSCell may constantly be in a starting state. The pSCellis a cell capable of receiving the PUCCH.

In the dual connectivity, a Data Radio Bearer (DRB) may be individuallyallocated to the MeNB and the SeNB. On the other hand, a Signaling RadioBearer (SRB) may be allocated only to the MeNB. In the dualconnectivity, a duplex mode may be configured individually for the MCGand the SCG or the PCell and the pSCell. In the dual connectivity, theMCG and the SCG or the PCell and the pSCell need not necessarily besynchronized with each other. In the dual connectivity, multipleparameters for timing adjustment (TAG or Timing Advance Group) may beconfigured for each of the MCG and the SCG. In other words, the terminaldevice is capable of performing uplink transmission at the multipledifferent timings in each CG.

In the dual connectivity, the terminal device is allowed to transmit UCIcorresponding to the cells in the MCG only to the MeNB (the PCell) andto transmit UCI corresponding to the cells in the SCG only to the SeNB(the pSCell). For example, the UCI is an SR, HARQ-ACK, and/or CSI.Additionally, in each UCI transmission, a transmission method using thePUCCH and/or the PUSCH is applied to each cell group.

All signals can be transmitted and received in the Primary cell, butsome signals may not be transmitted and received in the Secondary cell.For example, the Physical Uplink Control Channel (PUCCH) is transmittedonly in the Primary cell. Additionally, unless multiple Timing AdvanceGroups (TAGs) are configured between the cells, a Physical Random AccessChannel (PRACH) is transmitted only in the Primary cell. Additionally, aPhysical Broadcast Channel (PBCH) is transmitted only in the Primarycell. Additionally, a Master Information Block (MIB) is transmitted onlyin the Primary cell. Signals that can be transmitted and received in thePrimary cell are transmitted and received in the Primary Secondary cell.For example, the PUCCH may be transmitted in the Primary Secondary cell.Additionally, the PRACH may be transmitted in the Primary Secondarycell, regardless of whether the multiple TAGs are configured.Additionally, the PBCH and the MIB may be transmitted in the PrimarySecondary cell.

In the Primary cell, a Radio Link Failure (RLF) is detected. In theSecondary cell, even in a case where conditions for the detection of theRLF are in place, the detection of the RLF is not recognized. However,in the Primary Secondary cell, the RLF is detected in a case where theconditions are in place. When the RLF is detected in the PrimarySecondary cell, the higher layer of the Primary Secondary cell notifiesthe higher layer of the Primary cell of that the RLF has been detected.Semi-Persistent Scheduling (SPS) or Discontinuous Reception (DRX) may beperformed in the Primary cell. The same DRX as in the Primary cell maybe performed in the Secondary cell. Fundamentally, in the Secondarycell, the MAC configuration information/parameters are shared with thePrimary cell/Primary Secondary cell of the same cell group. Some of theparameters (e.g., sTAG-Id) may be configured for each Secondary cell.Some of the timers or counters may be applied only to the Primary celland/or the Primary Secondary cell. A timer or counter to be applied maybe configured only in the Secondary cell.

In an example of a case that the dual connectivity is applied to the LAAcell, the MCG (base station device 2-1) is a base station deviceconstituting the Primary cell, and the SCG (base station device 2-2) isa base station device constituting the LAA cell. Specifically, the LAAcell is configured as the pSCell of the SCG.

In another example of the case that the dual connectivity is applied tothe LAA cell, the MCG is a base station device constituting the Primarycell, and the SCG is a base station device constituting the pSCell andLAA cell. Specifically, the LAA cell is assisted by the pSCell in theSCG. Note that when a Secondary cell is further configured in the SCG,the LAA cell may be assisted by the Secondary cell.

In another example of the case that the dual connectivity is applied tothe LAA cell, the MCG is a base station device constituting the Primarycell and LAA cell, and the SCG is a base station device constituting thepSCell. Specifically, the LAA cell is assisted by the Primary cell inthe MCG. Note that when a Secondary cell is further configured in theMCG, the LAA cell may be assisted by the Secondary cell.

FIG. 3 is a schematic diagram illustrating an example of a blockconfiguration of the base station device 2 according to the presentembodiment. The base station device 2 includes a higher layer(higher-layer control information notification unit, higher layerprocessing unit) 501, a control unit (base station control unit) 502, acodeword generation unit 503, a downlink subframe generation unit 504,an OFDM signal transmission unit (downlink transmission unit) 506, atransmit antenna (base station transmit antenna) 507, a receive antenna(base station receive antenna) 508, an SC-FDMA signal reception unit(CSI reception unit) 509, and an uplink subframe processing unit 510.The downlink subframe generation unit 504 includes a downlink ReferenceSignal generation unit 505. Moreover, the uplink subframe processingunit 510 includes an uplink control information extraction unit (CSIacquisition unit) 511.

FIG. 4 is a schematic diagram illustrating an example of a blockconfiguration of the terminal device 1 according to the presentembodiment. The terminal device 1 includes a receive antenna (terminalreceive antenna) 601, an OFDM signal reception unit (downlink receptionunit) 602, a downlink subframe processing unit 603, a transport blockextraction unit (data extraction unit) 605, a control unit (terminalcontrol unit) 606, a higher layer (higher-layer control informationacquisition unit, higher layer processing unit) 607, a channel statemeasurement unit (CSI generation unit) 608, an uplink subframegeneration unit 609, SC-FDMA signal transmission units (UCI transmissionunits) 611 and 612, and transmit antennas (terminal transmit antennas)613 and 614. The downlink subframe processing unit 603 includes adownlink Reference Signal extraction unit 604. Moreover, the uplinksubframe generation unit 609 includes an uplink control informationgeneration unit (UCI generation unit) 610.

First, a flow of downlink data transmission and reception will bedescribed with reference to FIG. 3 and FIG. 4. In the base stationdevice 2, the control unit 502 holds a Modulation and Coding Scheme(MCS) indicating a modulation scheme, a coding rate, and the like in thedownlink, downlink resource allocation indicating RBs to be used fordata transmission, and information to be used for HARQ control (aRedundancy Version, an HARQ process number, and a new data indicator)and controls the codeword generation unit 503 and downlink subframegeneration unit 504 based on these elements. The downlink data (alsoreferred to as a downlink transport block) transmitted from the higherlayer 501 is processed through error correction coding, rate matching,and the like in the codeword generation unit 503 under the control ofthe control unit 502 and then, a codeword is generated. Two codewords atmaximum are transmitted at the same time in a single subframe of asingle cell. In the downlink subframe generation unit 504, a downlinksubframe is generated in accordance with an instruction from the controlunit 502. First, a codeword generated in the codeword generation unit503 is converted into a modulation symbol sequence through a modulationprocess, such as Phase Shift Keying (PSK) modulation or QuadratureAmplitude Modulation (QAM). Moreover, the modulation symbol sequence ismapped to the REs in some RBs, and a downlink subframe for each antennaport is generated through a precoding process. In this operation, atransmission data sequence transmitted from the higher layer 501includes higher-layer control information, which is control informationon the higher layer (e.g., dedicated (individual) Radio Resource Control(RRC) signaling). Moreover, in the downlink Reference Signal generationunit 505, a downlink Reference Signal is generated. The downlinksubframe generation unit 504 maps the downlink Reference Signal to theREs in the downlink subframes in accordance with an instruction from thecontrol unit 502. The downlink subframe generated in the downlinksubframe generation unit 504 is modulated to an OFDM signal in the OFDMsignal transmission unit 506 and then transmitted via the transmitantenna 507. Although a configuration of including one OFDM signaltransmission unit 506 and one transmit antenna 507 is provided as anexample here, a configuration of including multiple OFDM signaltransmission units 506 and transmit antennas 507 may be employed whendownlink subframes are transmitted on multiple antenna ports. Moreover,the downlink subframe generation unit 504 may also have the capabilityof generating physical-layer downlink control channels, such as a PDCCHand an EPDCCH, to map the channels to the REs in downlink subframes. Themultiple base station devices (base station device 2-1 and base stationdevice 2-2) transmit separate downlink subframes.

In the terminal device 1, an OFDM signal is received by the OFDM signalreception unit 602 via the receive antenna 601, and an OFDM demodulationprocess is performed on the signal. The downlink subframe processingunit 603 first detects physical-layer downlink control channels, such asa PDCCH and an EPDCCH. More specifically, the downlink subframeprocessing unit 603 decodes the signal by assuming that a PDCCH and anEPDCCH have been transmitted in the regions to which the PDCCH and theEPDCCH can be allocated, and checks Cyclic Redundancy Check (CRC) bitsadded in advance (blind decoding). In other words, the downlink subframeprocessing unit 603 monitors a PDCCH and an EPDCCH. When the CRC bitsmatch an ID (a single terminal-specific identifier assigned to a singleterminal, such as a Cell-Radio Network Temporary Identifier (C-RNTI) ora Semi-Persistent Scheduling-C-RNTI (SPS-C-RNTI), or a Temporary C-RNTI)assigned by the base station device in advance, the downlink subframeprocessing unit 603 recognizes that a PDCCH or an EPDCCH has beendetected and extracts a PDSCH by using control information included inthe detected PDCCH or EPDCCH. The control unit 606 holds an MCSindicating a modulation scheme, a coding rate, and the like in thedownlink based on the control information, downlink resource allocationindicating RBs to be used for downlink data transmission, andinformation to be used for HARQ control, and controls the downlinksubframe processing unit 603, the transport block extraction unit 605,and the like based on these elements. More specifically, the controlunit 606 performs control so as to carry out an RE mapping process inthe downlink subframe generation unit 504, an RE demapping process anddemodulation process corresponding to the modulation process, and thelike. The PDSCH extracted from the received downlink subframe istransmitted to the transport block extraction unit 605. The downlinkReference Signal extraction unit 604 in the downlink subframe processingunit 603 extracts the downlink Reference Signal from the downlinksubframe. In the transport block extraction unit 605, a rate matchingprocess, a rate matching process corresponding to error correctioncoding, error correction decoding, and the like in the codewordgeneration unit 503 are carried out, and a transport block is extractedand transmitted to the higher layer 607. The transport block includesthe higher-layer control information, and the higher layer 607 notifiesthe control unit 606 of a necessary physical-layer parameter based onthe higher-layer control information. The multiple base station devices2 (base station device 2-1 and base station device 2-2) transmitseparate downlink subframes, and the terminal device 1 receives thedownlink subframes. Hence, the above-described processes may be carriedout for the downlink subframe of each of the multiple base stationdevices 2. In this case, the terminal device 1 may recognize thatmultiple downlink subframes have been transmitted from the multiple basestation devices 2, or need not recognize this. In a case that theterminal device 1 does not recognize the above, the terminal device 1may simply recognize that multiple downlinks subframes have beentransmitted from multiple cells. Moreover, the transport blockextraction unit 605 determines whether the transport block has beendetected correctly and transmits the determination result to the controlunit 606.

Next, a flow of uplink signal transmission and reception will bedescribed. In the terminal device 1, a downlink Reference Signalextracted by the downlink Reference Signal extraction unit 604 istransmitted to the channel state measurement unit 608 under theinstruction from the control unit 606, the channel state and/orinterference is measured in the channel state measurement unit 608, andfurther CSI is calculated based on the measured channel state and/orinterference. The control unit 606 instructs the uplink controlinformation generation unit 610 to generate an HARQ-ACK (DTX (nottransmitted yet), ACK (detection succeeded), or NACK (detection failed))and map the resultant to a downlink subframe based on the determinationresult of whether the transport block is correctly detected. Theterminal device 1 performs these processes on the downlink subframe ofeach of multiple cells. In the uplink control information generationunit 610, a PUCCH including the calculated CSI and/or HARQ-ACK isgenerated. In the uplink subframe generation unit 609, the PUSCHincluding the uplink data transmitted from the higher layer 607 and thePUCCH generated by the uplink control information generation unit 610are mapped to the RBs in an uplink subframe to generate an uplinksubframe. The uplink subframe is subjected to the SC-FDMA modulation togenerate an SC-FDMA signal, and the SC-FDMA signal is transmitted viathe transmit antenna 613 by the SC-FDMA signal transmission unit 611.

The LAA cell is described in detail below.

Frequencies used by the LAA cell are shared by other communicationsystems and/or other LTE operators. In frequency sharing, fairness amongthe LAA cell and other communication systems and/or other LTE operatorsis needed. For example, a fair frequency sharing technique (method) isneeded in a communication scheme used by the LAA cell. In other words,the LAA cell is a cell in which a communication scheme (communicationprocedure) to which the fair frequency sharing technique is applicable(or usable for) is performed.

An example of the fair frequency sharing technique is Listen-Before-Talk(LBT). In the LBT, before a base station or terminal transmits a signalusing a frequency (component carrier, cell), an interference power ofthe frequency (interference signal, received power, received signal,noise power, or noise signal) or the like is measured (or detected) toidentify (detect, presume, or determine) whether the frequency is in anidle state (available state, congested state, Presence, or Occupied), ora busy state (unavailable state, not-congested state, Absence, orClear). In a case that the frequency is identified as being in the idlestate based on the LBT, the LAA cell can transmit a signal at thefrequency at a prescribed timing. In a case that the frequency isidentified as being in the busy state based on the LBT, the LAA celldoes not transmit a signal at the frequency at a prescribed timing. TheLBT makes it possible to control to not interfere the signalstransmitted by other base stations and/or terminals including othercommunication systems and/or other LTE operators.

A procedure of the LBT is defined as a mechanism to which a CCA check isapplied before a base station or a terminal uses the frequency(channel). In the CCA, the power or signal is detected for decidingwhether other signals are present on the channel in order to identifywhether the frequency is in the idle state or the busy state. Note thatthe definition of CCA may be equivalent to the definition of LBT in thepresent embodiment.

In the CCA, a method for deciding the presence/absence of other signalsmay include various methods. For example, in the CCA, thepresence/absence of other signals is decided based on whether aninterference power at a frequency exceeds a threshold. Moreover, forexample, in the CCA, the presence/absence of other signals is decidedbased on whether a prescribed signal at a frequency or a received poweron a channel exceeds a threshold. The threshold may be defined inadvance. The threshold may be configured by the base station or otherterminals. The threshold may be decided (configured) at least based onother value (parameter) such as a transmit power (maximum transmitpower).

Note that the CCA in the LAA cell does not need to be recognized by theterminal connected (configured) to the LAA cell.

The LAA cell may be defined as a cell different from the Secondary cellwhere the Licensed spectrum is used. For example, the LAA cell isconfigured differently from the configuration of the Secondary cellwhere the Licensed spectrum is used. Some parameters configured to theLAA cell are not configured to the Secondary cell where the Licensedspectrum is used. Some parameters configured to the Secondary cell wherethe Licensed spectrum is used are not configured to the LAA cell. In thepresent embodiment, the LAA cell is described as a cell different fromthe Primary cell and Secondary cell, but the LAA cell may be defined asone of the Secondary cells. The Secondary cell of the related art isalso referred to as a “first Secondary cell”, and the LAA cell is alsoreferred to as a “second Secondary cell”. The Primary cell and Secondarycell of the related art are also referred to as a “first Serving cell”,and the LAA cell is also referred to as a “second Serving cell”.

The LAA cell may be different from the frame structure type of therelated art. For example, in the Serving cell of the related art, afirst frame structure type (FDD, frame structure type 1) or a secondframe structure type (TDD, frame structure type 2) is used (configured),but in the LAA cell, a third frame structure type (frame structure type3) is used (configured).

Here, the Unlicensed spectrum is a frequency different from the Licensedspectrum allocated as a proprietary frequency to a prescribed operator.For example, the Unlicensed spectrum is a frequency used by a wirelessLAN. For example, the Unlicensed spectrum is a frequency not configuredin the LTE of the related art, and the Licensed spectrum is a frequencyconfigurable in the LTE of the related art. In the present embodiment,the frequency configured in the LAA cell is described as the Unlicensedspectrum, but is not limited thereto. Specifically, the Unlicensedspectrum may be replaced with the frequency configured in the LAA cell.For example, the Unlicensed spectrum is a frequency not configurable inthe Primary cell, but is a frequency configurable only in the Secondarycell. For example, the Unlicensed spectrum includes a frequency sharedby multiple operators. For example, the Unlicensed spectrum is afrequency configured only to a cell which is subjected to aconfiguration, presumption and/or process different from those in thePrimary cell or Secondary cell of the related art.

The LAA cell may be a cell where a scheme different from scheme of therelated art is used concerning the configuration of a radio frame, aphysical signal, and/or physical channel and the like and communicationprocedure in LTE.

For example, in the LAA cell, a prescribed signal and/or channelconfigured (transmitted) in the Primary cell and/or Secondary cell isnot configured (transmitted). The prescribed signal and/or channelincludes the CRS, DS, PDCCH, EPDCCH, PDSCH, PSS, SSS, PBCH, PHICH,PCFICH, CSI-RS and/or SIB, and the like. For example, signals and/orchannels not configured in the LAA cell are as below. Note that thesignal and/or channel described below may be used in combination. Notethat in the present embodiment, the signal and/or channel not configuredin the LAA cell may read as the signal and/or channel which the terminaldoes not expect transmission from the LAA cell.

(1) In the LAA cell, the control information in a physical layer istransmitted not on the PDCCH but only on the EPDCCH.

(2) In the LAA cell, even in a subframe in an activation state (ON), theCRS, DMRS, URS, PDCCH, EPDCCH and/or PDSCH are not transmitted at any ofthe subframes, and the terminal does not presume the transmission atevery subframe.

(3) In the LAA cell, the terminal presumes that the DRS, PSS, and/or SSSis transmitted at the subframe in the activation state (ON).

(4) In the LAA cell, the terminal is notified of information on themapping of the CRS for each subframe, and presumes the mapping of theCRS based on the information. For example, in the presumed mapping ofthe CRS, the CRS is not mapped to all the Resource Elements of thesubframe. In the presumed mapping of the CRS, the CRS is not mapped tosome of the Resource Elements of the subframe (e.g., all ResourceElements of the first 2 OFDM symbols). In the presumed mapping of theCRS, the CRS is mapped to all the Resource Elements of the subframe. Forexample, the information on the mapping of the CRS is notified from theLAA cell or a cell different from the LAA cell. The information on themapping of the CRS is included in the DCI, and notified by the PDCCH orEPDCCH.

For example, in the LAA cell, a prescribed signal and/or channel notconfigured (transmitted) in the Primary cell and/or Secondary cell isconfigured (transmitted).

For example, in the LAA cell, only the downlink component carrier orsubframe is defined to transmit only the downlink signal and/or channel.In other words, in the LAA cell, the uplink component carrier orsubframe is not defined and the uplink signal and/or channel is nottransmitted.

Moreover, for example, a Downlink Control Information (DCI) formatcompliant with the LAA cell is different from a DCI format compliantwith the Primary cell and/or Secondary cell. The DCI format compliantwith only the LAA cell is defined. The DCI format compliant with the LAAcell includes the control information effective only in the LAA cell.

For example, in the LAA cell, presumption of the signal and/or channelis different from those in the Secondary cell of the related art.

First, the presumption of the signal and/or channel in the Secondarycell of the related art is described. The terminal satisfying some orall of conditions below presumes that the PSS, SSS, PBCH, CRS, PCFICH,PDSCH, PDCCH, EPDCCH, PHICH, DMRS and/or CSI-RS may not be transmittedby the Secondary cell except for the DS transmission. The terminalpresumes that the DS is always transmitted by the Secondary cell. Thepresumption is continued until a subframe at which an activation command(a command for activation) is received by the terminal in the Secondarycell at a certain carrier frequency.

(1) The terminal supports the configuration (parameter) concerning theDS.

(2) RRM measurement based on the DS is configured to the terminal in theSecondary cell.

(3) The Secondary cell is in a deactivation state (deactivated state).

(4) The terminal is not configured to receive MBMS by the higher layerin the Secondary cell.

In a case that the Secondary cell is in the activation state (activatedstate), the terminal presumes that the PSS, SSS, PBCH, CRS, PCFICH,PDSCH, PDCCH, EPDCCH, PHICH, DMRS and/or CSI-RS are transmitted at theconfigured prescribed subframes or all of the subframes by the Secondarycell.

Next, an example of the presumption of the signal and/or channel in theLAA cell is described. The terminal satisfying some or all of conditionsbelow presumes that transmission of the PSS, SSS, PBCH, CRS, PCFICH,PDSCH, PDCCH, EPDCCH, PHICH, DMRS and/or CSI-RS as well as the DStransmission may not be performed by LAA cell. The presumption iscontinued until a subframe at which an activation command (a command foractivation) is received by the terminal in the Secondary cell at acertain carrier frequency.

(1) The terminal supports the configuration (parameter) concerning theDS.

(2) RRM measurement based on the DS is configured to the terminal in theLAA cell.

(3) The LAA cell is in a deactivation state (deactivated state).

(4) The terminal is not configured to receive MBMS by the higher layerin the LAA cell.

Furthermore, another example of the presumption of the signal and/orchannel in the LAA cell is described. In a case that the LAA cell is inthe deactivation (deactivated state), the presumption of the signaland/or channel in the LAA cell is the same as the presumption of thesignal and/or channel in the Secondary cell of the related art. In acase that the LAA cell is in the activation (activated state), thepresumption of the signal and/or channel in the LAA cell is differentfrom the presumption of the signal and/or channel in the Secondary cellof the related art. For example, in the case that the LAA cell is in theactivation state (activated state), the terminal presumes that the PSS,SSS, PBCH, CRS, PCFICH, PDSCH, PDCCH, EPDCCH, PHICH, DMRS and/or CSI-RSmay not be transmitted by the LAA cell at a subframe other than theprescribed subframes configured by the LAA cell. Details thereof isdescribed later.

Next, a communication procedure in the LAA cell is described in detail.In the LAA cell, channel and/or signal transmission can be started basedon the LBT at timing independent of a Subframe boundary. Moreover, inthe LAA cell, channel and/or signal transmission can be ended based onthe LBT and the maximum burst length for which transmission is possible,at timing independent of the Subframe boundary. In other words, thechannel and/or the signal can be transmitted at a partial subframe. Thepartial subframe can be defined, for example, as follows. Here, in thepresent embodiment, OFDM symbols, at which transmission is possible,indicated by the partial subframe can be defined as a symbol. At thesymbol, it is presumed that the terminal transmits each of or all thechannels and/or the signals.

(1) In a subframe, transmission is possible at the area from an OFDMsymbol in the middle of the subframe to the last OFDM symbol of thesubframe (Subframe boundary). In the present embodiment, the area isalso referred to as a first partial subframe.

(2) In a subframe, transmission is possible at the area from the firstOFDM symbol of the subframe (Subframe boundary) to an OFDM symbol in themiddle of the subframe. In the present embodiment, the area is alsoreferred to as a second partial subframe.

(3) In a subframe, transmission is possible at the area from an OFDMsymbol in the middle of the subframe to an OFDM symbol in the middle ofthe subframe. In the present embodiment, the area is also referred to asa third partial subframe.

Moreover, in the partial subframe, the number of OFDM symbols in themiddle of the subframe can be limited to a prescribed number. Forexample, the prescribed number is 2, 3, and/or 4.

In a case that the prescribed number is 2, the partial subframe can beset to one slot or one subframe (two slots), for example. In otherwords, the time direction unit of the second EPDCCH is one slot or onesubframe. In a case that the time direction unit of the second EPDCCH isone slot, the time direction unit of the PDSCH scheduled by the secondEPDCCH can also be one slot. In other words, a communication method(scheme) using one subframe as a unit as in the LTE of the related artand a communication method using one slot, which is half of that in theLTE of the related art, are used while being switched appropriately.Using one slot as a unit can reduce latency in radio communication. Thisallows a communication method capable of reducing latency in radiocommunication to be achieved in addition to a communication methodsimilar to the LTE of the related art. This can be applied not only tothe LAA cell but also the LTE of the related art used in the Licensedspectrum. Hence, all the methods and constitutions described in thepresent embodiment can be applied not only to the LAA cell but also theLTE of the related art used for the Licensed spectrum.

Here, in the LAA cell, in a case that the channel and/or signaltransmission is enabled, the period in which the LAA cell can performtransmission is defined based on the LBT. The period is also referred toas a maximum burst length, and the channel and/or the signal transmittedin the period is also referred to as burst. For example, the maximumburst length is 4 ms (four subframe length). Hence, in each burst, thefirst subframe of the burst is a first partial subframe, and the lastsubframe of the burst is a second partial subframe. Note that eachpartial subframe is also referred to as a floating subframe.Additionally, each partial subframe may be a subframe including asymbol/subframe at which channel and/or signal described in the presentembodiment is not transmitted (cannot be transmitted).

In a subframe, the subframe at which transmission is possible in thearea from the first OFDM symbol in the subframe (Subframe boundary) tothe last OFDM symbol in the subframe (Subframe boundary), is alsoreferred to as a full subframe. The full subframe is a subframe otherthan partial subframes. In each burst, the full subframe is a subframeother than the first subframe of the burst or the last subframe of theburst. The full subframe may be a subframe not including anysymbol/subframe at which the channel and/or the signal described in thepresent embodiment is not transmitted (cannot be transmitted). Moreover,the full subframe in the LAA cell may be a subframe having the sameconfiguration and/or a subframe at which the same processing as that ofa normal subframe in a normal cell is performed.

FIG. 5 is a diagram illustrating an example of a communication procedurein an LAA cell. FIG. 5 illustrates 10 subframes designated as subframes#0 to #9, and 14 symbols (OFDM symbols) designated as symbols #0 to #13in the subframe #3. In this example, the LAA cell can transmit a signalup to 4 ms (corresponding to 4 subframes), and the CCA is performed onthe symbol #5 in the subframe #3. Assume that the LAA cell identifiesthat the frequency is in the idle state through the CCA and a signal canbe transmitted at symbols immediately after the identification. In FIG.5, the LAA cell transmits the signals at the symbols from the symbol #6in the subframe #3 to a prescribed symbol in the subframe #6.

In FIG. 5, the symbol or subframe represented as the symbol/subframe atwhich the channel and/or signal is not transmitted (cannot betransmitted) indicates that the LAA transmits nothing. In FIG. 5, thesymbol or subframe represented as the symbol/subframe at which thechannel and/or signal is transmitted (can be transmitted) indicates thatthe LAA transmits at least a PDSCH, and a terminal-specific ReferenceSignal associated with the PDSCH. The PDSCH is mapped (scheduled) toeach terminal using a resource block pair as a unit. Information on themapping (scheduling) is notified via the PDCCH or EPDCCH transmitted ateach subframe. The mapping information for a PDSCH at a subframe may benotified at the identical subframe or at another subframe.

In FIG. 5, in a case that the LAA cell transmits a PDSCH using thesymbol #6 to #13 in the subframe #3, the terminal receiving the PDSCHneeds to recognize that the PDSCH is mapped to the symbol #6 to #13 inthe subframe #3.

An example of the recognition uses information for recognizing a symbolat which a channel and/or signal is transmitted in a prescribed subframe(e.g., subframe #3) in the LAA cell. For example, the information is anyor a combination of the following information.

(1) The information is information indicating a start symbol in thesymbols at which the channel and/or signal is transmitted in theprescribed subframe. The information indicating the start symbol is anyof 0 to 13, each value of which indicates a symbol number of a symbol tobe the start symbol.

(2) The information is information indicating a start symbol in thesymbols at which the channel and/or signal is transmitted in theprescribed subframe. The information indicating the start symbol isindex information in which values predefined from values 0 to 13 areindexed.

(3) The information is bitmap information indicating symbols at whichthe channel and/or signal is transmitted in the prescribed subframe. Thebitmap information is constituted by 14 bits. In the bitmap information,in a case that a bit has one state (e.g., “1”), the bit indicates thesymbol at which the channel and/or signal is transmitted, and in a casethat a bit has the other state (e.g., “0”), the bit indicates the symbolat which the channel and/or signal is not transmitted.

(5) The information is information indicating an end symbol in thesymbols at which the channel and/or signal is not transmitted in theprescribed subframe, or information indicating the number of symbols ofthe symbols at which the channel and/or signal is not transmitted. Forexample, the end symbol is any of 0 to 13, and each value of whichindicates a symbol number of a symbol to be the end symbol. For example,the information indicating the number of symbols is any of 1 to 14, andeach value of which indicates the number of the symbols.

(6) The information is information indicating an end symbol in thesymbols at which the channel and/or signal is not transmitted in theprescribed subframe, or information indicating the number of symbols ofthe symbols at which the channel and/or signal is not transmitted. Forexample, the end symbol is index information in which values predefinedfrom values 0 to 13 are indexed. For example, the information indicatingthe number of symbols is index information in which values predefinedfrom values 1 to 14 are indexed.

A method for notifying the information for recognizing the symbol atwhich the channel and/or signal is transmitted employs any of methodsdescribed as below, for example.

(1) The information is notified using the parameter configured(notified) to the LAA cell by way of RRC signaling or MAC signaling. Ina case that a Serving cell is an LAA cell, the channel and/or signal isnot transmitted at a symbol configured in a subframe, and the channeland/or signal is transmitted at other symbols. For example, the symbolsat which the channel and/or signal is not transmitted are configured asthe symbols #0 and #1 in a subframe. The symbols at which the channeland/or signal is not transmitted are configured as the symbols #2 and#13 in a subframe. This configuration may be different (independent)depending on the channel and/or signal. For example, the terminal isconfigured such that the EPDCCH is mapped to the symbols #2 to #13 andthe PDSCH is mapped to the symbols #1 to #13 in a subframe. Moreover,for example, a range of the start symbol of the PDSCH (possible values)configured to the LAA cell may be different from a range (1 to 4) of thestart symbol of the PDSCH configured to the Secondary cell of therelated art. The range of the start symbol of the PDSCH and/or EPDCCHconfigured to the LAA cell is 0 to 13.

(2) The information is notified using a PDCCH or EPDCCH transmitted fromthe LAA cell or the Serving cell different from the LAA cell (assistcell, Primary cell, or Secondary cell). The DCI carried (transmitted) bythe PDCCH or EPDCCH includes the information.

(3) The information is notified using a channel or signal for notifyingthe information. The channel or signal for notifying the information istransmitted only to the LAA cell. The channel or signal for notifyingthe information is transmitted from the LAA cell or the Serving celldifferent from the LAA cell (assist cell, Primary cell, or Secondarycell).

(4) Candidates for the information are configured (notified) to the LAAcell by way of RRC signaling or MAC signaling. Selection is made fromamong the candidates for the information based on the informationincluded in the DCI carried (transmitted) by the PDCCH or EPDCCH. Forexample, the information indicating 4 start symbols is configured by wayof RRC signaling or MAC signaling, and 2-bit information indicating oneof the information pieces is notified by way of PDCCH or EPDCCHsignaling.

(5) The information is notified using a channel or signal mapped toprescribed Resource Elements in a subframe. For example, the prescribedResource Elements are multiple Resource Elements in a prescribed symbol.For example, the prescribed symbol is an end symbol in the subframe. Thesubframe to which the channel or signal for notifying the information ismapped may be all the subframes in the LAA cell, a predefined subframe,or a subframe configured by way of RRC signaling.

(6) The information is predefined. In a case that a Serving cell is anLAA cell, the channel and/or signal is not transmitted at a prescribedsymbol, and the channel and/or signal is transmitted at other symbols ina subframe. For example, the symbols at which the channel and/or signalis not transmitted are the symbols #0 and #1 in a subframe. The symbolsat which the channel and/or signal is not transmitted are the symbols #2and #13 in a subframe. This definition may be different (independent)depending on the channel and/or signal. For example, the terminalpresumes that the EPDCCH is mapped to the symbols #2 to #13 and thePDSCH is mapped to the symbols #1 to #13 in a subframe.

In another example of the recognition, the terminal detects a symbol atwhich a channel and/or signal is transmitted in a prescribed subframe(e.g., subframe #3) in the LAA cell. In the terminal, assist informationmay be configured for performing the detection. For example, a method ofthe detection employs any of methods described as below.

(1) The detection is performed based on a prescribed signal mapped tothe prescribed subframe. The terminal detects the symbol at which thechannel and/or signal is transmitted based on whether the predefinedsignal or the configured signal is detected in the prescribed subframe.In a case that the predefined signal or configured signal is detected ata symbol in the prescribed subframe, the terminal recognizes subsequentsymbols of the symbol in the prescribed subframe as the symbols at whichthe channel and/or signal is transmitted. For example, the predefinedsignal or the configured signal is the CRS, DMRS, and/or URS.

(2) The detection is performed based on a prescribed channel mapped tothe prescribed subframe. The terminal detects the symbol at which thechannel and/or signal is transmitted based on whether the predefinedchannel or the configured channel is detected in the prescribedsubframe. In a case that the predefined channel or the configuredchannel is detected at a symbol in the prescribed subframe, the terminalrecognizes subsequent symbols of the symbol in the prescribed subframeas the symbols at which the channel and/or signal is transmitted. Forexample, the predefined channel or the configured channel is the EPDCCH.Specifically, the terminal presumes that the EPDCCH is mapped to asymbol and subsequent symbols in the prescribed subframe to performmonitoring of the EPDCCH (detection process, blind detection). Here, theterminal may perform the blind detection on the start symbol where theEPDCCH is presumed to be mapped. The start symbol or candidates of thestart symbol where the EPDCCH is presumed to be mapped may be predefinedor configured.

In FIG. 5, a method for mapping the PDCCH, EPDCCH and/or PDSCH to theResource Element in the subframe #3 may be different from a mappingmethod in other subframes. For example, the mapping method may employany of methods described below. Note that the mapping methods below(mapping procedure) may be applied also to other signals such as theReference Signal or the synchronization signal.

(1) In the mapping method, the PDCCH, EPDCCH and/or PDSCH are mapped tofrom the end symbol in the subframe. In other words, mapping the PDCCH,EPDCCH and/or PDSCH to the Resource Element (k, l) is performed onsymbols in order from the OFDM symbol having the maximum OFDM symbolnumber 1 (i.e., the end symbol in a slot) in the Resource Elementcapable of mapping and being an allocated physical resource block. Themapping is performed in order from the end slot in the subframe (thesecond slot). In each OFDM symbol, those channels are mapped in orderfrom a subcarrier having the minimum subcarrier number k.

(2) In the mapping method, the PDCCH, EPDCCH and/or PDSCH are mapped tothe Resource Element in the symbol at which the channel and/or signal istransmitted while the symbol at which the channel and/or signal is nottransmitted is skipped. In other words, in mapping of the PDCCH, EPDCCHand/or PDSCH, the Resource Element in the symbol at which the channeland/or signal is not transmitted is subjected to the rate matching.

(3) In the mapping method, the PDCCH, EPDCCH and/or PDSCH are mapped tothe Resource Element in the symbol at which the channel and/or signal istransmitted while the symbol at which the channel and/or signal is nottransmitted is not skipped. In other words, the PDCCH, EPDCCH and/orPDSCH are mapped without distinguishing the symbol at which the channeland/or signal is transmitted from the symbol at which the channel and/orsignal is not transmitted, but the channel is not transmitted that ismapped to the symbol at which the channel and/or signal is nottransmitted, and the channel is transmitted that is mapped to the symbolat which the channel and/or signal is transmitted. Specifically, inmapping the PDCCH, EPDCCH and/or PDSCH, the Resource Element in thesymbol at which the channel and/or signal is not transmitted issubjected to puncturing.

FIG. 6 is a diagram illustrating an example of a communication procedurein an LAA cell. Hereinafter, differences from the contents describedwith reference to FIG. 5 are described. In this example, the CCA isperformed on the symbol #5 in the subframe #3. Assume that the LAA cellidentifies that the frequency is in the idle state through the CCA and asignal can be transmitted at symbols immediately after theidentification. The LAA cell transmits the signals at the symbols fromthe symbol #5 in the subframe #3 to a prescribed symbol in the subframe#6.

In the example in FIG. 6, the symbols #6 and #7 in the subframe #3 aresymbols at which a reservation signal is transmitted. The reservationsignal is transmitted at the symbols from a symbol immediately after thesymbol to be subjected to the CCA (i.e., symbol #5) to a symbolimmediately before the symbol at which the channel and/or signal istransmitted (i.e., symbol #6). Effects of the reservation signal are asbelow. As described with reference to FIG. 5, even in the case that thecandidates of the symbol at which the channel and/or signal istransmitted are predefined or configured, the LAA cell can flexiblyperform the CCA independently from the number of the candidates.

The reservation signal may not be received (recognized) even by theterminal which receives the channel and/or signal transmitted from theLAA cell. In other words, in a case that the channel and/or signalcannot be transmitted after performing the CCA, the reservation signalis transmitted for the LAA cell, which has performed the CCA, to ensure(reserve) the frequency.

To the symbol at which the reservation signal is transmitted, a channeland/or signal may be mapped which is different from the channel and/orsignal transmitted at the symbol at which the channel and/or signal istransmitted. In other words, the channel and/or signal mapped to thesymbol at which the reservation signal is transmitted is recognized(received) by the terminal. For example, the terminal identifies thesymbol at which the channel and/or signal is transmitted, based on thechannel and/or signal mapped to the symbol at which the reservationsignal is transmitted. Moreover, for example, the terminal uses thechannel and/or signal mapped to the symbol at which the reservationsignal is transmitted to synchronize with (identify) the LAA cell.

A reservation signal in the present embodiment is also referred to as aninitial signal. The initial signal is a signal transmitted at thebeginning of a burst and can be distinguished from the PDSCH, theEPDCCH, the PDCCH, and/or a Reference Signal in the burst. In addition,the initial signal can include control information on the burst, controlinformation on a channel and/or a signal in the burst, or controlinformation on the cell transmitting the burst.

FIG. 7 is a diagram illustrating an example of a communication procedurein an LAA cell. Hereinafter, differences from the contents describedwith reference to FIG. 5 are described. In this example, the CCA isperformed on the symbol #5 in the subframe #3 as is the example in FIG.5. Assume that the LAA cell identifies that the frequency is in the idlestate through the CCA and a signal can be transmitted at symbolsimmediately after the identification. In FIG. 7, the LAA cell transmitsthe signals at from the symbol #6 in the subframe #3 to the symbol #5 inthe subframe #7 after 4 ms.

In the example in FIG. 7, the LAA cell transmits the reservation signalat the symbols from a symbol immediately after the symbol to besubjected to the CCA to the end symbol in the subframe including thesymbol to be subjected to the CCA. The LAA cell transmits the channeland/or signal at subframes subsequent to the subframe including thesymbol to be subjected to the CCA. The reservation signal in FIG. 7includes the reservation signal described with reference to FIG. 6.

For example, in FIG. 7, the terminal can presume that the channel and/orsignal is transmitted at the subframe #4 and subsequent subframes. Thiscauses the terminal to presume that the channel and/or signal istransmitted at the symbols started from the first symbol in thesubframe. Therefore, the base stations including LAA cell can use thesame method as those of the related art for the terminal with respect tothe transmission of the channel and/or signal and notification of thecontrol information for the channel and/or signal.

In FIG. 7, the LAA cell can transmit the channel and/or signal at thesymbols from the first symbol to the symbol #5 in the subframe #7. Forexample, the LAA cell can transmit to the terminal the PDSCH and/orEPDCCH mapped to resources from a prescribed symbol to the symbol #5 insubframe #7. The LAA cell can transmit to the terminal the PDCCH mappedto resources from the first symbol to a prescribed symbol in thesubframe #7. For example, a prescribed symbol is determined based oninformation transmitted on the PCFICH and on the number of OFDM symbolsused to transmit the PDCCH. Moreover, for example, a prescribed symbolis determined based on information which is the control informationconfigured by way of RRC signaling and indicates an OFDM start symbolwhich is for the EPDCCH, the PDSCH scheduled by the PDCCH, and the PDSCHscheduled by the EPDCCH.

In FIG. 7, the LAA cell can notify or configure to the terminal the endsymbol at which the channel and/or signal is transmitted in the subframe#7. In a subframe in the LAA cell, for the information for the terminalto recognize the end symbol and the method for notifying theinformation, those described in the example in FIG. 5 can be used. Themethod described in the example in FIG. 5 relates to the information forrecognizing the symbol at which the channel and/or signal is transmittedin FIG. 5 and the method for notifying the information. For example, inthe LAA cell, the information on the end symbol is included in the DCInotified by the PDCCH or EPDCCH transmitted at the subframe #7. Thisallows the LAA cell to efficiently use the resource in the case that thechannel and/or signal can be transmitted at the symbols until a symbolin the middle of the subframe as is the subframe #7 in FIG. 7. Forexample, in the LAA cell, the information on the end symbol is includedin information configured by way of RRC signaling or MAC signaling.

In FIG. 7, a method is described to be used as a combination of thetransmission method in the subframe #3 and the transmission method inthe subframe #7, but is not limited thereto. The transmission method insubframe #3 and the transmission method in the subframe #7 may be usedindependently from each other. Some or all of the methods described withreference to FIGS. 5 to 7 may be used in combination.

Moreover, in the subframe #7 in FIG. 7, the mapping of the PDCCH, EPDCCHand/or PDSCH to the Resource Element may be different from the mappingin other subframes.

In the LAA cell, a subframe where the channel and/or signal can betransmitted at all the OFDM symbols in the single subframe itself (i.e.,the subframes #4 to #6 in FIGS. 5 to 7) may be recognized, configured,or notified as a subframe different from a subframe where the channeland/or signal cannot be transmitted at some OFDM symbols in the singlesubframe itself (i.e., the subframe #3 in FIGS. 5 to 7, and the subframe#7 in FIG. 7). For example, a subframe where the channel and/or signalcan be transmitted at all the OFDM symbols in the single subframe itselfis equivalent to a subframe in the Serving cell of the related art.

In the present embodiment, a subframe where the channel and/or signalcannot be transmitted at all the OFDM symbols in the single subframeitself is also referred to as a “first LAA subframe”. A subframe wherethe channel and/or signal cannot be transmitted at some OFDM symbols inthe single subframe itself is also referred to as a “second LAAsubframe”. A subframe where the channel and/or signal can be transmittedat all the OFDM symbols in the single subframe itself is also referredto as a “third LAA subframe”. Moreover, the second LAA subframe is alsoreferred to as a partial subframe, and the third LAA subframe is alsoreferred to as a full subframe. Note that the second LAA subframeincludes the first partial subframe, the second partial subframe, and/orthe third partial subframe.

The method described in the present embodiment can be used for a methodfor the terminal to recognize the first LAA subframe, the second LAAsubframe, and the third LAA subframe. For example, the method forrecognizing the subframes uses the information for recognizing thesymbol at which the channel and/or signal is transmitted and the methodfor notifying the information.

The method for the terminal to recognize the first LAA subframe, thesecond LAA subframe, and the third LAA subframe may be explicitlynotified or configured by way of PDCCH or RRC signaling.

The method for the terminal to recognize the first LAA subframe, thesecond LAA subframe, and the third LAA subframe may be implicitlynotified or configured based on the information (parameter) notified orconfigured by way of PDCCH or RRC signaling. For example, the terminalrecognizes the first LAA subframe, the second LAA subframe, and thethird LAA subframe based on the information on the mapping of the CRS.

In a case that the terminal recognizes a subframe as the second LAAsubframe, the terminal recognizes a prescribed number of subframessubsequent to the subframe as the third LAA subframes. The terminalrecognizes, as the first LAA subframes, subframes subsequent to the endof the subframes which are recognized as the third LAA subframes untilthe terminal recognizes the second LAA subframes. The prescribed number(i.e., the number of subframes recognized as the third LAA subframes)may be predefined. The prescribed number may be configured in the LAAcell. The prescribed number may be notified using the channel and/orsignal mapped to the second LAA subframe.

In the second LAA subframe and the third LAA subframe, the start symbolof the PDSCH and/or EPDCCH is independently defined or configured.

FIGS. 5 to 7 illustrate that the CCA is performed on a single subframe,but a time (period) for performing the CCA is not limited thereto. Thetime for performing the CCA may vary for each LAA cell, for each timingof the CCA, or for each execution of the CCA. For example, the CCA isperformed at the time based on a prescribed time slot (time period, timedomain). The prescribed time slot may be defined or configured by a timeobtained by dividing a single subframe into a prescribed number ofsections. The prescribed time slot may be defined or configured by aprescribed number of subframes.

In the present embodiment, a size of a field in the time domain such asthe time (time slot) for performing the CCA, or a time when the channeland/or signal is transmitted (can be transmitted) at a subframe can berepresented using a prescribed time unit. For example, the size of thefield in the time domain is represented as some time units Ts. Ts is1/(15000*2048) sec. For example, a time of a single subframe is 30720*Ts(1 ms).

As is the subframe #3 in the FIGS. 5 to 7, whether the LAA cell cantransmit the channel and/or signal (including the reservation signal) atthe symbols from the middle of symbols in the subframe may be configuredto the terminal or LAA cell. For example, in the configurationconcerning the LAA cell, information is configured to the terminal, theinformation indicating whether RRC signaling allows such a transmission.The terminal switches, based on the information, the processesconcerning the reception in the LAA cell (monitoring, recognition,decoding).

The subframe capable of the transmission from the middle of symbols(including the subframe capable of the transmission until the middle ofthe symbols) may be all the subframes in the LAA cell. The subframecapable of the transmission from the middle of symbols may be a subframepredefined or subframe configured to the LAA cell.

The subframe capable of the transmission from the middle of symbols(including the subframe capable of the transmission until the middle ofthe symbols) can be configured, notified, or decided based on the TDDuplink/downlink configuration (UL/DL configuration). For example, such asubframe is a subframe notified (specified) as the special subframe bythe UL/DL configuration. The special subframe in the LAA cell is asubframe including at least one of three fields, a Downlink Pilot TimeSlot (DwPTS), a Guard Period (GP), and an Uplink Pilot Time Slot(UpPTS). The configuration concerning the special subframe in the LAAcell may be configured or notified by way of RRC signaling, or PDCCH orEPDCCH signaling. This configuration configures a time length withrespect to at least one of the DwPTS, GP, and UpPTS. This configurationis index information indicating candidates of a predefined time length.Further, this configuration can use the same time length as the DwPTS,GP, and UpPTS used for the special subframe configuration configured tothe TDD cell of the related art. In other words, the time length capableof transmission at a subframe is determined based on any of the DwPTS,GP, and UpPTS.

In the present embodiment, the reservation signal may be a signal whichcan be received by a LAA cell different from the LAA cell transmittingthe reservation signal. For example, a LAA cell different from the LAAcell transmitting the reservation signal is a LAA cell (adjacent LAAcell) adjacent to the LAA cell transmitting the reservation signal. Forexample, the reservation signal includes information on a transmissionstate (usage state) of a prescribed subframe and/or symbol in the LAAcell. In a case that an LAA cell different from the LAA celltransmitting a reservation signal receives the reservation signal, theLAA cell that has received the reservation signal recognizes atransmission state of a prescribed subframe and/or symbol based on thereservation signal to perform scheduling depending on the state.

The LAA cell that has received the reservation signal may perform theLBT before transmitting the channel and/or signal. The LBT is performedbased on the received reservation signal. For example, in the LBT,scheduling including the resource allocation or the MCS selection isperformed, taking into account the channel and/or signal transmitted(presumed to be transmitted) by the LAA cell that has transmitted thereservation signal.

In a case that the LAA cell that has received the reservation signalperforms scheduling of transmitting the channel and/or signal based onthe reservation signal, information on the scheduling can be notified toone or more LAA cells including the LAA cell that has transmitted thereservation signal according to a prescribed method. For example, theprescribed method is a method of transmitting a prescribed channeland/or signal including the reservation signal. Moreover, for example,the prescribed method is a method of notifying via a backhaul such asthe X2 interface.

In the carrier aggregation and/or dual connectivity, the terminal of therelated art can configure up to 5 Serving cells, but the terminal in thepresent embodiment can extend the maximum number of Serving cells to beconfigured. In other words, more than 5 Serving cells can be configuredto the terminal in the present embodiment. For example, up to 16 or 32Serving cells can be configured to the terminal in the presentembodiment. For example, more than 5 Serving cells configured to theterminal in the present embodiment include the LAA cell. Moreover, allof more than 5 Serving cells configured to the terminal in the presentembodiment may be the LAA cells.

In the case that more than 5 Serving cells can be configured, theconfiguration for some Serving cells may be different from theconfiguration of the Serving cell of the related art (i.e., theSecondary cell of the related art). For example, the following pointsare different regarding the configuration. The configurations describedbelow may be used in combination.

(1) Up to 5 Serving cells of the related art and up to 11 or 27 Servingcells different from the Serving cell of the related art are configuredto the terminal. In other words, up to 4 Secondary cells of the relatedart, and 11 or 27 Secondary cells different from the Secondary cell ofthe related art are configured to the terminal, in addition to thePrimary cell of the related art.

(2) The configuration concerning the Serving cell (Secondary cell)different from the Serving cell of the related art includes theconfiguration concerning the LAA cell. For example, up to 4 Secondarycells excluding the configuration concerning the LAA cell, and up to 11or 27 Secondary cells different from the Secondary cell of the relatedart are configured to the terminal, in addition to the Primary cell ofthe related art.

Further, in the case that more than 5 Serving cells can be configured,the base station (including the LAA cell) and/or terminal can performthe process or presumption different from those in the case that up to 5Serving cells are configured. For example, the following points aredifferent regarding the process or presumption. The processes orpresumptions described below may be used in combination.

(1) Even in the case that more than 5 Serving cells are configured, theterminal presumes that the PDCCH, EPDCCH and/or PDSCH are simultaneouslytransmitted (received) from 5 Serving cells at most. This allows theterminal to use the method similar to those of the related art regardingthe reception of the PDCCH, EPDCCH and/or PDSCH, and the transmission ofthe HARQ-ACK in response to the PDSCH.

(2) In the case that more than 5 Serving cells are configured, acombination (group) of cells for bundling the HARQ-ACKs in response tothe PDSCH in the Serving cells is configured to the terminal. Forexample, all the Serving cells, all the Secondary cells, all the LAAcells, or all the Secondary cells different from the Secondary cell ofthe related art include information (configuration) on bundling of theHARQ-ACKs between the Serving cells. For example, the information onbundling of the HARQ-ACKs between the Serving cells is an identifier(index, ID) for the bundling. For example, the HARQ-ACKs are bundledover cells with the same identifier for the bundling. The bundling isperformed by an AND operation on the target HARQ-ACKs. The maximumnumber of identifiers for the bundling may be set to 5. The maximumnumber of identifiers for the bundling may be set to 5 including thenumber of cells not performing the bundling. In other words, the numberof groups performing bundling across the Serving cells may be set to 5at most. This allows the terminal to use the method similar to those ofthe related art regarding the reception of the PDCCH, EPDCCH and/orPDSCH, and the transmission of the HARQ-ACK in response to the PDSCH.

(3) In the case that more than 5 Serving cells are configured, acombination (group) of cells for multiplexing the HARQ-ACKs in responseto the PDSCH in the Serving cells is configured to the terminal. In thecase that the combination (group) of cells for multiplexing theHARQ-ACKs in response to the PDSCH is configured, the multiplexedHARQ-ACKs are transmitted on the PUCCH or PUSCH based on the group. Ineach group, the maximum number of multiplexed Serving cells is definedor configured. The maximum number is defined or configured based on themaximum number of Serving cells configured to the terminal. For example,the maximum number is the same as the maximum number of Serving cellsconfigured to the terminal, or half of the maximum number of Servingcells configured to the terminal. The maximum number of PUCCHssimultaneously transmitted is defined or configured based on the maximumnumber of Serving cells multiplexed in each group, and the maximumnumber of Serving cells configured to the terminal.

In other words, the number of first Serving cells (i.e., Primary celland/or Secondary cell) to be configured is equal to or less than aprescribed number (i.e., “5”), and the total number of first Servingcells and the second Serving cells (i.e., LAA cells) to be configuredexceeds the prescribed number.

Next, a terminal capability relating to the LAA is described. Theterminal notifies the base station of (transmits to the base station)information on a capability of the terminal (terminal capability) by wayof RRC signaling based on an instruction from the base station. Theterminal capability with respect to a function (feature) is notified(transmitted) in a case that the function (feature) is supported, and isnot notified (not transmitted) in a case that the function (feature) isnot supported. The terminal capability with respect to a function(feature) may be information indicating whether a test and/orimplementation of the function (feature) is completed. For example, theterminal capability in the present embodiment is as below. The terminalcapabilities described below may be used in combination.

(1) The terminal capability concerning support of the LAA cell and theterminal capability concerning support of the configuration of more than5 Serving cells are defined independently from each other. For example,the terminal supporting the LAA cell supports the configuration of morethan 5 Serving cells. In other words, the terminal not supporting theconfiguration of more than 5 Serving cells does not support the LAAcell. In this case, the terminal supporting the configuration of morethan 5 Serving cells may or may not support the LAA cell.

(2) The terminal capability concerning the support of the LAA cell andthe terminal capability concerning the support of the configuration ofmore than 5 Serving cells are defined independently from each other. Forexamples, the terminal supporting the configuration of more than 5Serving cells supports the LAA cell. In other words, the terminal notsupporting the LAA cell does not support the configuration of more than5 Serving cells. In this case, the terminal supporting the LAA cell mayor may not support the configuration of more than 5 Serving cells.

(3) The terminal capability concerning the downlink in the LAA cell andthe terminal capability concerning the uplink in the LAA cell aredefined independently from each other. For example, the terminalsupporting the uplink in the LAA cell supports the downlink in the LAAcell. In other words, the terminal not supporting the downlink in theLAA cell does not support the uplink in the LAA cell. In this case, theterminal supporting the downlink in the LAA cell may or may not supportthe uplink in the LAA cell.

(4) The terminal capability concerning the support of the LAA cellincludes support of the transmission mode configured only to the LAAcell.

(5) The terminal capability concerning the downlink in the configurationof more than 5 Serving cells and the terminal capability concerning theuplink in the configuration of more than 5 Serving cells are definedindependently from each other. For example, the terminal supporting theuplink in the configuration of more than 5 Serving cells supports thedownlink in the configuration of more than 5 Serving cells. In otherwords, the terminal not supporting the downlink in the configuration ofmore than 5 Serving cells does not support the uplink in theconfiguration of more than 5 Serving cells. In this case, the terminalsupporting the downlink in the configuration of more than 5 Servingcells may or may not support the uplink in the configuration of morethan 5 Serving cells.

(6) In the terminal capability in the configuration of more than 5Serving cells, the terminal capability supporting the configuration ofup to 16 downlink Serving cells (component carriers) and the terminalcapability supporting the configuration of up to 32 downlink Servingcells are defined independently from each other. The terminal supportingthe configuration of up to 16 downlink Serving cells supports theconfiguration of at least one uplink Serving cell. The terminalsupporting the configuration of up to 32 downlink Serving cells supportsthe configuration of at least two uplink Serving cells. In other words,the terminal supporting the configuration of up to 16 downlink Servingcells may not support the configuration of two or more uplink Servingcells.

(7) The terminal capability concerning the support of the LAA cell isnotified based on the frequency (band) used in the LAA cell. Forexample, in notification of a frequency or a combination of frequenciessupported by the terminal, in a case that the frequency or thecombination of frequencies to be notified includes at least onefrequency used in the LAA cell, the terminal implicitly notifies thebase station of supporting the LAA cell. In other words, in a cast thatthe frequency or the combination of frequencies to be notified does notinclude any frequency used in the LAA cell at all, the terminalimplicitly notifies the base station of not supporting the LAA cell.

Next, a terminal capability relating to the second EPDCCH is described.In an example of the terminal capability according to the presentembodiment, the field of the terminal capability relating to the secondEPDCCH defines whether the terminal is capable of receiving a DCI in theUSS and/or the CSS in the second EPDCCH. Specifically, in a case thatthe terminal is capable of receiving the DCI in the USS and/or the CSSin the second EPDCCH, the terminal makes a notification indicating“Supported” in the field of the terminal capability relating to thesecond EPDCCH. In contrast, in a case that the terminal is not capableof receiving the DCI in the USS and/or the CSS in the second EPDCCH, theterminal does not make any notification in the field of the terminalcapability relating to the second EPDCCH.

In a case that the terminal is capable of receiving the DCI in the USSand/or the CSS in the second EPDCCH, the terminal has the capability ofreceiving the DCI in the USS in the first EPDCCH. Specifically, in acase that the terminal makes a notification indicating “Supported” inthe field of the terminal capability relating to the second EPDCCH, theterminal makes a notification indicating “Supported” in the field of theterminal capability relating to the first EPDCCH. In addition, in a casethat the terminal makes a notification indicating “Supported” in thefield of the terminal capability relating to the second EPDCCH, theterminal may indicate that the terminal has the capability of receivingthe DCI in the USS in the first EPDCCH.

In a case that the terminal is capable of receiving the DCI in the USSand/or the CSS in the second EPDCCH, the terminal also has thecapability relating to the LAA (including, for example, those describedabove). Specifically, in a case that the terminal makes a notificationindicating “Supported” in the field of the terminal capability relatingto the second EPDCCH, the terminal makes a notification indicating“Supported” in the field of the terminal capability relating to the LAA.In addition, in a case that the terminal makes a notification indicating“Supported” in the field of the terminal capability relating to thesecond EPDCCH, the terminal may indicate that the terminal has thecapability relating to the LAA.

In the present embodiment, a description is given of a case that the LAAcell transmits the PDCCH or EPDCCH notifying the DCI for the PDSCHtransmitted by the LAA cell (i.e., a case of self-scheduling), but thepresent embodiment is not limited thereto. For example, the methoddescribed in the present embodiment can be applied also to a case thatthe Serving cell different from the LAA cell transmits the PDCCH orEPDCCH notifying the DCI for the PDSCH transmitted by the LAA cell(i.e., a case of cross carrier scheduling).

In the present embodiment, information for recognizing the symbol atwhich the channel and/or signal is transmitted may be based on thesymbol at which the channel and/or signal is not transmitted. Forexample, the information is information indicating the end symbol in thesymbols at which the channel and/or signal is not transmitted. Moreover,the information for recognizing the symbol at which the channel and/orsignal is transmitted may be determined based on other information orparameters.

In the present embodiment, the symbol at which the channel and/or signalis transmitted may be configured (notified, or defined) independentlyfrom the channel and/or signal. In other words, the information forrecognizing the symbol at which the channel and/or signal is transmittedand the method for notifying the information can be configured(notified, or defined) independently from the channel and/or signal. Forexample, the information for recognizing the symbol at which the channeland/or signal is transmitted and the method for notifying theinformation can be configured (notified, or defined) independently bythe PDSCH and the EPDCCH.

In the present embodiment, the symbol/subframe at which the channeland/or signal is not transmitted (cannot be transmitted) may be thesymbol/subframe at which the channel and/or signal is not presumed, fromthe viewpoint of the terminal, to be transmitted (transmittable). Inother words, the terminal can assume that the LAA cell is nottransmitting the channel and/or signal at the symbol/subframe.

Moreover, in the present embodiment, the symbol/subframe at which thechannel and/or signal is transmitted (can be transmitted) may be thesymbol/subframe at which the channel and/or signal is presumed, from theviewpoint of the terminal, to be possibly transmitted. In other words,that terminal can assume that the LAA cell may or may not betransmitting the channel and/or signal at the symbol/subframe.

Further, in the present embodiment, the symbol/subframe at which thechannel and/or signal is transmitted (can be transmitted) may be thesymbol/subframe at which the channel and/or signal is presumed, from theviewpoint of the terminal, to be surely transmitted. In other words, theterminal can assume that the LAA cell is surely transmitting the channeland/or signal at the symbol/subframe.

In the present embodiment, the LAA cell may be a Serving cell using aprescribed frequency band.

Next, an Enhanced Physical Downlink Control Channel (EPDCCH) will bedescribed. Note that the EPDCCH, as other physical channels such as aPDSCH, is transmitted/received using Resource Elements (REs). Each ofelements (each element corresponding to one subcarrier and one OFDMsymbol) of a resource grid (representing a signal to be transmitted in agrid constituted of subcarriers and OFDM symbols for each slot) for anantenna port P is referred to as an RE and is uniquely identified usingk (an index starting from 0 and being numbered in ascending order in thefrequency axis direction) and 1 (an index starting from 0 and beingnumbered in ascending order in the time axis direction) representing apair of indexes in one slot.

The EPDCCH may be different in terms of configuration and/or processingamong the normal subframe in the normal cell, the partial subframe inthe LAA cell, and/or the full subframe in the LAA cell. For example, inthe partial subframe, an EPDCCH constituted of OFDM symbols, the numberof which is smaller than that of an EPDCCH used in the normal subframeand/or the full subframe, is used. In the present embodiment, the EPDCCHused in the normal subframe is also referred to as a first EPDCCH, andthe EPDCCH used in the partial subframe is also referred to as a secondEPDCCH. Note that, in the full subframe, the first EPDCCH and/or thesecond EPDCCH may be used.

FIG. 8 illustrates an example of an EREG configuration in one RB pair.The Enhanced RE Groups (EREGs) are used to specify mapping of an EPDCCHto REs. Each of resource block pairs includes 16 EREGs numbered from 0to 15. In one PRB pair, all REs excluding REs at which DMRSs for antennaports 107, 108, 109, and 110 for a normal Cyclic Prefix (CP) and for theantenna ports 107 and 108 for an extended CP are carried, are cyclicallynumbered from 0 to 15 in ascending order of, first, frequency, thentime. In FIG. 8, Resource Elements shaded with oblique lines are used tocarry DMRSs. All the REs numbered i in the PRB pair constitute the EREGsnumbered i. Here, the CP is a signal attached in front of an effectivesymbol section of OFDM symbols in the downlink (or SC-FDMA symbols inthe case of the uplink), and is a signal including a copy of part(normally the last part) of the effective symbol section. There are twokinds of CP lengths, one is for a normal CP of a normal length (e.g.,160 samples or 144 samples in a case that the effective symbol length is2048 samples) and the other is for an extended CP, which is longer thanthe normal CP (e.g., 512 samples or 1024 samples in a case that theeffective symbol length is 2048 samples).

Here, the same EREG configuration can be used for the first EPDCCH orthe second EPDCCH. Specifically, for each resource block pair, the EREGsin the first EPDCCH or the second EPDCCH are specified for all REsexcluding REs at which a DMRS for antenna ports 107, 108, 109, and 110for a normal Cyclic Prefix (CP) and for the antenna ports 107 and 108for an extended CP are carried. With this configuration, even in a casewhere different DMRS configurations are used, the definitions forconfiguring EREGs are the same although REs for configuring the EREGsare different from each other.

As illustrated in FIG. 8, one RB pair is constituted of two RBs. Each RBis constituted of Resource Elements represented by 7 OFDM symbols in thetime direction and 12 subcarriers in the frequency direction. In FIG. 8,DMRSs are mapped to the Resource Elements shaded with oblique lines.Moreover, each DMRS is constituted of two-chip orthogonal code, and upto two DMRSs can be code-division multiplexed. The DMRSs for the antennaports 107 and 108 are mapped to REs having the OFDM symbol numbers 5 and6 and the subcarrier numbers 0, 5, and 10 in each slot. The DMRSs forthe antenna ports 109 and 110 are mapped to REs having the OFDM symbolnumbers 5 and 6 and the subcarrier numbers 1, 6, and 11 in each slot.Here, as a DMRS associated with the first EPDCCH, the DMRSs described inFIG. 8 can be used.

As an example of a DMRS associated with the second EPDCCH, the DMRSsdescribed in FIG. 8 can be used. Specifically, in the DMRS associatedwith the second EPDCCH, a similar configuration as that of the DMRSassociated with the first EPDCCH can be used, but, in a case that theDMRS is included in the OFDM symbols at which the second EPDCCH cannotbe transmitted, the DMRS is not transmitted. For example, in the partialsubframes with OFDM symbols #0 to #6 in slot 1, the DMRS associated withthe second EPDCCH is mapped only to OFDM symbols #5 and #6 in slot 1 andis not mapped only to #5 and #6 in slot 0. In a case that the DMRScannot be transmitted at any OFDM symbol of the two OFDM symbols towhich two-chip orthogonal code is mapped, the DMRS is presumed not to betransmitted.

Another example of the DMRS associated with the second EPDCCH isdetermined based on OFDM symbols to be used for transmission of thesecond EPDCCH. Specifically, each of the REs to which the DMRSassociated with the second EPDCCH is mapped is specified depending onthe configuration of the OFDM symbols to be used for transmission of thesecond EPDCCH. A prescribed number of patterns of the configuration ofthe OFDM symbols to be used for transmission of the second EPDCCH can bepredefined. Hence, a prescribed number of patterns of the configurationof the DMRS associated with the second EPDCCH can be predefinedsimilarly.

FIGS. 9A to 9E are diagrams illustrating examples of a configuration ofDMRSs associated with the second EPDCCH used for the first partialsubframe. In FIGS. 9A to 9E, the REs shaded with oblique lines representREs to which the DMRSs associated with the second EPDCCH are mapped. TheREs shaded with dots represent REs (OFDM symbols) not used fortransmission of the second EPDCCH. Specifically, in FIG. 9A, OFDM symbol#0 in slot 0 is the starting symbol for the second EPDCCH; in FIG. 9B,OFDM symbol #3 in slot 0 is the starting symbol for the second EPDCCH:in FIG. 9C, OFDM symbol #0 in slot 1 is the starting symbol for thesecond EPDCCH; in FIG. 9D, OFDM symbol #0 in slot 1 is the startingsymbol for the second EPDCCH; in FIG. 9E, OFDM symbol #3 in slot 1 isthe starting symbol for the second EPDCCH. As illustrated in FIGS. 9A to9E, the configuration of the DMRSs associated with the second EPDCCH canbe defined depending on the starting symbol for the second EPDCCH.

FIGS. 10A to 10E are diagrams illustrating examples of a configurationof the DMRSs associated with the second EPDCCH used for the secondpartial subframe. In FIGS. 10A to 10E, the REs shaded with oblique linesrepresent REs to which the DMRSs associated with the second EPDCCH aremapped. The REs shaded with dots represent REs (OFDM symbols) not usedfor transmission of the second EPDCCH. Specifically, in FIG. 10A, OFDMsymbol #6 in slot 1 is the end symbol of the second EPDCCH; in FIG. 10B,OFDM symbol #3 in slot 1 is the end symbol of the second EPDCCH; in FIG.10C, OFDM symbol #1 in slot 1 is the end symbol of the second EPDCCH; inFIG. 10D, OFDM symbol #6 in slot 0 is the end symbol of the secondEPDCCH; in FIG. 10E, OFDM symbol #4 in slot 0 is the end symbol of thesecond EPDCCH. As illustrated in FIGS. 10A to 10E, the configuration ofthe DMRSs associated with the second EPDCCH can be defined depending onthe end symbol of the second EPDCCH. Additionally, the configuration ofthe DMRSs associated with the second EPDCCH used for the second partialsubframe can be the same as the configuration of the DMRSs used for theDwPTS.

The EPDCCH carries scheduling assignment. One EPDCCH is transmitted byusing an aggregation of one or some contiguous Enhanced Control ChannelElements (ECCEs). Here, each ECCE is constituted of multiple EREGs. Thenumber of ECCEs used for one EPDCCH depends on the format of the EPDCCHand the number of EREGs of each ECCE. Both localized transmission anddistributed transmission are supported. One EPDCCH can use any oflocalized transmission and distributed transmission using differentmodes of mapping to the EREGs of the ECCEs and the PRB pair.

In the first EPDCCH, either localized transmission or distributedtransmission can be configured via RRC signaling for each EPDCCH set. Inthe second EPDCCH, either localized transmission or distributedtransmission can be predefined for each of all the EPDCCH sets. Forexample, in the second EPDCCH, distributed transmission can bepredefined for all the EPDCCH sets.

As described later, the terminal device monitors multiple EPDCCHs.Setting of one or two PRB pairs in which the terminal device monitorsEPDCCH transmission is possible. As configured by a higher layer, onlylocalized transmission or only distributed transmission uses all EPDCCHcandidates in an EPDCCH set X_(m). In EPDCCH set X_(m) in subframe i,ECCEs available for EPDCCH transmission are numbered from 0 toN_(ECCE,m,i)−1. Here, N_(ECCE,m,i) represents the number of ECCEsavailable for EPDCCH transmission in EPDCCH set X_(m) in subframe i. TheECCE numbered n corresponds to the EREG numbered (n mod N^(RB)_(ECCE))+jN^(RB) _(ECCE) in the PRB having floor(n/N^(RB) _(ECCE)) as anindex in the case of localized mapping and corresponds to the EREGnumbered floor(n/N^(Xm) _(RB))+jN^(RB) _(ECCE) in the PRB having (n+jmax(1, N^(Xm) _(RB)/N^(ECCE) _(EREG))) mod N^(Xm) _(RB) as an index inthe case of distributed mapping. Here, j=0, 1, . . . , N^(ECCE)_(EREG)−1, and N^(ECCE) _(EREG) represents the number of EREGs per ECCE.Moreover, N^(RB) _(ECCE) is equal to 16/N^(ECCE) _(EREG) and representsthe number of ECCEs per PRB pair. Moreover, floor, mod, and maxrespectively represent floor function, modulo function (mod function),and maximum value function (max function). Note that the PRB pairsconstituting EPDCCH set X_(m) are assumed to be numbered from 0 toN^(Xm) _(RB)−1 in ascending order here.

In the first EPDCCH, N^(ECCE) _(EREG) is determined based on the CP andthe subframe type. More specifically, in the case of a normal CP and anormal subframe (normal downlink subframe) or the case of a normal CPand a special subframe with special subframe configuration 3, 4, or 8,N^(ECCE) _(EREG) is 4. In the case of a normal CP and a special subframewith special subframe configuration 1, 2, 6, 7, or 9 (in other words, aspecial subframe in which the DwPTS is constituted of 6 or greater and10 or less OFDM symbols), the case of an extended CP and a normalsubframe, or the case of an extended CP and a special subframe withspecial subframe configuration 1, 2, 3, 5, or 6 (in other words, aspecial subframe in which the DwPTS is constituted of 6 or greater and10 or less OFDM symbols), N^(ECCE) _(EREG) is 8. Note that details ofthe special subframe configuration will be described later.

In an example of N^(ECCE) _(EREG) in the second EPDCCH, N^(ECCE) _(EREG)is a predefined value. For example, N^(ECCE) _(EREG) in the secondEPDCCH is 8 as in the case of a normal CP and a special subframe withspecial subframe configuration 1, 2, 6, 7, or 9 in the first EPDCCH.Moreover, for example, N^(ECCE) _(EREG) in the second EPDCCH is 16,which is the same number of EREGs constituted of one resource blockpair.

In another example of N^(ECCE) _(EREG) in the second EPDCCH, N^(ECCE)_(EREG) is determined depending on n_(EPDCCH) (to be described later) inthe detected (presumed or monitored) second EPDCCH. Specifically, in acase that n_(EPDCCH) in the second EPDCCH is a prescribed number orgreater, N^(ECCE) _(EREG) is 4 (or 8); and in a case that n_(EPDCCH) inthe second EPDCCH is less than the prescribed number, N^(ECCE) _(EREG)is 8 (or 16). The prescribed number may be predefined or may beconfigured in a cell-specific or UE-specific manner via RRC signaling.For example, the prescribed number is 104, which is the same as theprescribed number used in the first EPDCCH. Alternatively, for example,the prescribed number may be different from the prescribed number usedin the first EPDCCH.

Moreover, multiple prescribed numbers may be defined or configured forn_(EPDCCH). Specifically, in a case that n_(EPDCCH) in the second EPDCCHis a first prescribed number or greater, N^(ECCE) _(EREG) is 4; in acase that n_(EPDCCH) in the second EPDCCH is a second prescribed numberor greater and less than a first prescribed number, N^(ECCE) _(EREG) is8; and in a case that n_(EPDCCH) in the second EPDCCH is less than thesecond prescribed number, N^(ECCE) _(EREG) is 16. For example, the firstprescribed number is 104, which is the same as the prescribed numberused in the first EPDCCH. The second prescribed number is a value lessthan the first prescribed number.

In another example of N^(ECCE) _(EREG) in the second EPDCCH, N^(ECCE)_(EREG) is determined depending on the number of OFDM symbols in thedetected (presumed or monitored) second EPDCCH. Specifically, in a casethat the number of OFDM symbols in the second EPDCCH is a prescribednumber or greater, N^(ECCE) _(EREG) is 4 (or 8); and in a case that thenumber of OFDM symbols in the second EPDCCH is less than the prescribednumber, N^(ECCE) _(EREG) is 8 (or 16). The prescribed number may bepredefined or may be configured in a cell-specific or UE-specific mannervia RRC signaling.

Moreover, multiple prescribed numbers may be defined or configured forthe number of OFDM symbols. Specifically, in a case that the number ofOFDM symbols in the second EPDCCH is a first prescribed number orgreater, N^(ECCE) _(EREG) is 4; in a case that the number of OFDMsymbols in the second EPDCCH is a second prescribed number or greaterand less than the first prescribed number, N^(ECCE) _(EREG) is 8; and ina case that the number of OFDM symbols in the second EPDCCH is less thanthe second prescribed number, N^(ECCE) _(EREG) is 16. For example, thesecond prescribed number is a value less than the first prescribednumber.

In another example, N^(ECCE) _(EREG) in the second EPDCCH is determinedbased on the CP and the subframe type similar to that in the firstEPDCCH, but N^(ECCE) _(EREG) is a value twice as large as that of thefirst EPDCCH. More specifically, in the case of a normal CP and a normalsubframe (normal downlink subframe), or the case of a normal CP and aspecial subframe with special subframe configuration 3, 4, or 8,N^(ECCE) _(EREG) is 8. In the case of a normal CP and a special subframewith special subframe configuration of 1, 2, 6, 7, or 9 (in other words,a special subframe in which the DwPTS is constituted of 6 or greater and10 or less OFDM symbols), the case of an extended CP and a normalsubframe, or the case of an extended CP and a special subframe withspecial subframe configuration 1, 2, 3, 5, or 6 (in other words, aspecial subframe in which the DwPTS is constituted of 6 or greater and10 or less OFDM symbols), N^(ECCE) _(EREG) is 16.

The correspondence between the EPDCCH format and the number of ECCEs perEPDCCH (aggregation level) can be defined. The correspondence may bedefined differently for the first EPDCCH and the second EPDCCH.

The correspondence between the EPDCCH format and the number of ECCEs perEPDCCH (aggregation level) can be defined for multiple cases, case A andcase B, in the first EPDCCH. Case A is used in a case that a conditionfor case 1 to be described later is satisfied, and case B is usedotherwise. The aggregation levels in case A is 2, 4, 8, and 16 in thecase of localized transmission and 2, 4, 8, 16, and 32 in the case ofdistributed transmission. The aggregation levels in case B is 1, 2, 4,and 8 in the case of localized transmission and 1, 2, 4, 8, and 16 inthe case of distributed transmission. Hence, the aggregation levels incase A are higher than the aggregation levels in case B. With thisconfiguration, prescribed reception performance for the EPDCCH can beachieved by using a higher aggregation level even in a case that thenumber of REs used for each EREG in the EPDCCH is small.

n_(EPDCCH), which represents a quantity for a certain terminal device,is defined as the number of downlink REs satisfying all of or some ofcriteria (a1) to (a4) below in one PRB pair configured for EPDCCHtransmission in EPDCCH set X₀ (the first EPDCCH set of up to two EPDCCHsets).

(a1) The RE is part of any one of 16 EREGs in the PRB pair.

(a2) The RE is presumed not to be used for a CRS by the terminal device.Here, as long as no other values are provided for the parameters for thenumber of CRS antenna ports and frequency shift, the CRS position isgiven based on these parameters at the Serving cell (the number ofantenna ports based on the same antenna port configuration as that ofthe PBCH and the frequency shift obtained based on a Physical CellIdentifier). In contrast, in a case that the set of these parameters isconfigured in the terminal device based on re-MappingQCL-ConfigID-r11,which is a higher layer parameter, the CRS position is determined byusing the parameters.

(a3) The RE is presumed not to be used for a CSIRS by the terminaldevice. Here, the CSIRS position is given based on the configuration ofzero-power CSIRS in the Serving cell (in a case that no other value isprovided for the configuration for zero-power CSIRS) and theconfiguration of non-zero-power CSIRS. In contrast, in a case that thezero-power CSIRS is configured in the terminal device based onre-MappingQCL-ConfigID-r11, which is a higher layer parameter, the CSIRSposition is determined by using the parameter.

(a4) Index 1 in the first slot in the subframe satisfies 1_(EPDCCHStart)or greater. Specifically, mapping is performed to REs having OFDMsymbols having indexes of 1_(EPDCCHStart) and subsequent to1_(EPDCCHStart) in one subframe. Here, 1 is an index given to an OFDMsymbol in a slot, and numbered from 0 in ascending order in the timedirection from the first OFDM symbol in the slot. Description of1_(EPDCCHStart) will be given later.

In an example, the correspondence between the EPDCCH format and thenumber of ECCEs per EPDCCH (aggregation level) in the second EPDCCH isthe same as that of the first EPDCCH.

In another example of the correspondence between the EPDCCH format andthe number of ECCEs per EPDCCH (aggregation level) in the second EPDCCH,one case is predefined. For example, case A is predefined for thecorrespondence between the EPDCCH format and the number of ECCEs perEPDCCH (aggregation level) in the second EPDCCH.

In another example of the correspondence between the EPDCCH format andthe number of ECCEs per EPDCCH (aggregation level) in the second EPDCCH,multiple cases, case A, case B, and case C, can be defined. Theaggregation levels in case A and the aggregation levels in case B arethe same as those of the first EPDCCH. The aggregation levels in case Ccan be higher than the aggregation levels in case A. For example, theaggregation levels in case C are 4, 8, 16, and 32 in the case oflocalized transmission and 4, 8, 16, 32 and 64 in the case ofdistributed transmission.

In an example of n_(EPDDCH), which is a quantity for a specific terminaldevice, n_(EPDCCH) for the first EPDCCH and n_(EPDCCH) for the secondEPDCCH are independent from each other. In the first EPDCCH, n_(EPDCCH)is defined as the number of downlink REs satisfying all criteria (a1) to(a4) above in one PRB pair configured for EPDCCH transmission in EPDCCHset X₀ (the first EPDCCH set of up to two EPDCCH sets) in the firstEPDCCH. In addition, in the second EPDCCH, n_(EPDCCH) is defined as thenumber of downlink REs satisfying all or some of criteria (a1) to (a4)above in one PRB pair configured for EPDCCH transmission in EPDCCH setX₀ (the first EPDCCH set of one or more EPDCCH sets) in the secondEPDCCH.

In an example of n_(EPDDCH), which is a quantity for a specific terminaldevice, n_(EPDCCH) is common to the first EPDCCH and the second EPDCCH.Specifically, n_(EPDDCH) in the second EPDCCH is the same as n_(EPDDCH)in the first EPDCCH. This means that, in the second EPDCCH, n_(EPDCCH)is defined as the number of downlink REs satisfying all criteria (a1) to(a4) above in one PRB pair configured for EPDCCH transmission in EPDCCHset X₀ (the first EPDCCH set of up to two EPDCCH sets) in the firstEPDCCH.

b(0), . . . , b(M_(bit)−1) representing blocks of bits transmitted onone EPDCCH at one subframe are scrambled based on h(i)=(b(i)+c(i)) mod2, which results in h(0), . . . , h(M_(bit)−1), which are blocks ofscrambled bits. Here, M_(bit) represents the number of bits to betransmitted on one EPDCCH, and c(i) represents a UE-specific scramblingsequence initialized with parameter c_(init). This scrambling sequencegenerator is c_(init)=floor(n_(s)/2)2⁹+n^(EPDCCH) _(ID,m). m representsan EPDCCH set number. n_(S) represents a slot number in a radio frame.n^(EPDCCH) _(ID,m) represents a DMRS scrambling initialization parameterthat can be configured for each EPDCCH set via higher layer signalingand can take any value of 0 to 503.

h(0), . . . , h(M_(bit)−1), which are blocks of scrambled bits, aremodulated to be d(0), . . . , d(M_(symb)−1), which are blocks ofcomplex-valued modulation symbols. Here, M_(symb) represents the numberof modulation symbols transmitted on one EPDCCH. An EPDCCH modulationscheme is Quadrature Phase Shift Keying (QPSK). A block ofcomplex-valued modulation symbols is mapped to a single layer forprecoding based on a relational equation, y(i)=d(i). Here, i=0, . . .M_(symb)−1, and y represents a precoded modulation symbol.

y(0), . . . , y(M_(symb)−1), which are blocks of complex-valued symbols,are sequentially mapped to REs that satisfy all criteria (m1) to (m4)below and that are on associated antenna ports (REs at positions definedby k and l), starting from y(0).

(m1) The RE is part of an EREG allocated for EPDCCH transmission.

(m2) The RE is presumed not to be used for a CRS by the terminal device.Here, as long as no other values are provided for the parameters for thenumber of CRS antenna ports and frequency shift, the CRS position isgiven based on these parameters at the Serving cell (the number ofantenna ports based on the same antenna port configuration as that ofthe PBCH and the frequency shift obtained based on a Physical CellIdentifier). In contrast, in a case that the set of these parameters isconfigured in the terminal device based on re-MappingQCL-ConfigID-r11,which is a higher layer parameter, the CRS position is determined byusing the parameters.

(m3) The RE is presumed not to be used for a CSIRS by the terminaldevice. Here, the CSIRS position is given based on the configuration ofzero-power CSIRS in the Serving cell (in a case that no other value isprovided for the configuration for zero-power CSIRS) and theconfiguration of non-zero-power CSIRS. In contrast, in a case that thezero-power CSIRS is configured in the terminal device based onre-MappingQCL-ConfigID-r11, which is a higher layer parameter, the CSIRSposition is determined by using the parameter.

(m4) Index 1 in the first slot in the subframe being 1_(EPDCCHStart) orgreater is satisfied. Specifically, mapping is performed to REs on OFDMsymbols having indexes of 1_(EPDCCHStart) and subsequent to1_(EPDCCHStart) in one subframe. Here, 1 is an index given to an OFDMsymbol in a slot, and numbered from 0 in ascending order in the timedirection from the first OFDM symbol in the slot. Description of1_(EPDCCHStart) will be given later.

Mapping to REs (REs at positions defined by k and l) satisfying theabove criteria at antenna port P is performed in ascending order withrespect to index K first and then index l (in the direction that k and lincrease), which means that the mapping starts from the first slot andends at the second slot in the subframe.

Here, antenna port P is a logical antenna port. One antenna port maycorrespond to one physical antenna, or a signal of one antenna port mayactually be transmitted via multiple physical antennas. Alternatively,signals of multiple antenna ports may actually be transmitted via thesame physical antenna. In a case that the same antenna port is used, thesame channel performance can be achieved. Here, antenna ports 0 to 3 areantenna ports associated with (used for) CRS transmission, antenna port4 is an antenna port associated with (used for) transmission ofMultimedia Broadcast multicast service Single Frequency Network (MBSFN)Reference Signal, antenna ports 5 and 7 to 14 are antenna portsassociated with (used for) transmission of a UE-specific ReferenceSignal associated with a PDSCH, antenna ports 107 to 110 are antennaports associated with (used for) transmission of a DemodulationReference Signal associated with an EPDCCH, antenna port 6 is an antennaport associated with (used for) transmission of a positioning ReferenceSignal, and antenna ports 15 to 22 are antenna ports associated with(used for) transmission of CSIRS.

In localized transmission, single antenna port P to be used is given byn′, which is calculated based on n′=n_(ECCE,low) mod N^(RB)_(ECCE)+n_(RNTI) mod min(N^(EPDCCH) _(ECCE), N^(RB) _(ECCE)) and (n1) to(n4) below. Here, n_(ECCE,low) represents the smallest ECCE index usedfor this EPDCCH transmission in the EPDCCH set, and n_(RNTI) is equal toa Cell-RNTI (C-RNTI), which is one of Radio Network TemporaryIdentifiers (RNTIs). Moreover, N^(EPDCCH) _(ECCE) represents the numberof ECCEs used for this EPDCCH. Moreover, min represents the maximumvalue function (max function).

(n1) In the case of a normal CP, and a normal subframe or a specialsubframe with special subframe configuration 3, 4, or 8, n′=0corresponds to P=107. In the case of a normal CP and a special subframewith special subframe configuration 1, 2, 6, 7, or 9, n′=0 correspondsto P=107. In the case of an extended CP, n′=0 corresponds to P=107 forany subframe type.

(n2) In the case of a normal CP, and a normal subframe or a specialsubframe with special subframe configuration 3, 4, or 8, n′=1corresponds to P=108. In the case of a normal CP and a special subframewith special subframe configuration 1, 2, 6, 7, or 9, n′=1 correspondsto P=109. In the case of an extended CP, n′=1 corresponds to P=108 forany subframe type.

(n3) In the case of a normal CP, and a normal subframe or a specialsubframe with special subframe configuration 3, 4, or 8, n′=2corresponds to P=109.

(n4) In the case of a normal CP, and a normal subframe or a specialsubframe with special subframe configuration 3, 4, or 8, n′=3corresponds to P=110.

In distributed transmission, each of the REs in one EREG starts fromantenna port 107 and is associated with one of two antenna portsaccording to a rule indicating alternate use. Here, in a normal CP, thetwo antenna ports are antenna port 107 and an antenna port 109; in anextended CP, the two antenna ports are antenna port 107 and an antennaport 108.

For each Serving cell, a base station device can configure, for each UE,one or two EPDCCH-PRB sets (also referred to as groups of PRB pairs towhich an EPDCCH may be mapped or EPDCCH sets) for monitoring the EPDCCHvia higher layer signaling. Here, multiple PRB pairs corresponding toone EPDCCH-PRB set (the number of PRB pairs corresponding to oneEPDCCH-PRB set and the correspondence between the EPDCCH-PRB set and anyof PRB pairs) is also indicated via higher layer signaling. EachEPDCCH-PRB set is configured of a set of ECCEs numbered from 0 toN_(ECCE,p,k)−1. Here, N_(ECCE,p,k)−1 represents the number of ECCEs inEPDCCH-PRB set p (p+1-th EPDCCH-PRB set, p=0 or 1) in subframe k. Any oflocalized EPDCCH transmission and distributed EPDCCH transmission can beconfigured for each EPDCCH-PRB set. Specifically, one EPDCCH is mappedin the frequency direction relatively locally to the EPDCCH-PRB set forwhich localized EPDCCH transmission is configured, and one EPDCCH ismapped in the frequency direction in a relatively distributed manner tothe EPDCCH-PRB set for which distributed EPDCCH transmission isconfigured.

EPDCCH sets may be configured independently for the first EPDCCH and thesecond EPDCCH. For example, the EPDCCH set for the first EPDCCH and theEPDCCH set for the second EPDCCH may be configured by using differentparameters.

Moreover, the terminal may be configured so that the EPDCCH set for thefirst EPDCCH and the EPDCCH set for the second EPDCCH are not configuredat the same time in a Serving cell. For example, the EPDCCH set for thefirst EPDCCH is configured for a Serving cell using the LTE of therelated art, while the EPDCCH set for the second EPDCCH is configuredfor a LAA cell. Moreover, for example, in a case that a method (mode)using one subframe as a time direction unit as the LTE of the relatedart is configured for the terminal in the Serving cell, the EPDCCH setfor the first EPDCCH is configured; and in a case that a method (mode)using one slot as a time direction unit is configured, the EPDCCH setfor the second EPDCCH is configured.

Moreover, the terminal may be configured so that the EPDCCH set for thefirst EPDCCH and the EPDCCH set for the second EPDCCH are configured atthe same time in a Serving cell. For example, in a LAA cell, the firstEPDCCH is monitored based on the EPDCCH set for the first EPDCCH at apartial subframe, and the second EPDCCH is monitored based on the EPDCCHset for the second EPDCCH at a full subframe.

An example of different parameters with which the EPDCCH set for thefirst EPDCCH and the EPDCCH set for the second EPDCCH are configured isthe number of PRB pairs that can be configured for one EPDCCH set. Forexample, the number of PRB pairs that can be configured forcorresponding one EPDCCH set is 2, 4, or 8 in the EPDCCH set for thefirst EPDCCH. The number of PRB pairs that can be configured forcorresponding one EPDCCH set is 4, 8, or 16 in the EPDCCH set for thesecond EPDCCH, which is twice as large as that for the EPDCCH set forthe first EPDCCH. Alternatively, with respect to the EPDCCH set for thesecond EPDCCH, it may be defined so that the number of PRB pairscorresponding to one EPDCCH set may be defined according to the presumedstarting symbol or end symbol of the second EPDCCH. For example, it isdefined so that the number of PRB pairs corresponding to one EPDCCH setincreases as the number of OFDM symbols used for transmission of thesecond EPDCCH decreases.

An example of different parameters with which the EPDCCH set for thefirst EPDCCH and the EPDCCH set for the second EPDCCH are configured isa parameter relating to a partial subframe. For example, the parameterincludes a parameter indicating the starting symbol and/or the endsymbol of the second EPDCCH or a candidate therefor.

Moreover, as an example, the starting symbol for the second EPDCCH isconfigured independently or commonly for the individual EPDCCH sets viaRRC signaling. For example, as the starting symbol for the secondEPDCCH, one of OFDM symbols #0 to #6 in slot 0 and OFDM symbols #0 to #6in slot 1 is configured. Alternatively, for example, as the startingsymbol for the second EPDCCH, a prescribed number of candidates arepredefined from among OFDM symbols #0 to #6 in slot 0 and OFDM symbols#0 to #6 in slot 1, and any one of the candidates is configured.Alternatively, for example, as the starting symbol for the secondEPDCCH, any of OFDM symbol #0 in slot 0 and OFDM symbol #0 in slot 1 isconfigured. Alternatively, for example, the starting symbol for thesecond EPDCCH is determined based on an OFDM symbol at which an initialsignal has been detected. Specifically, the starting symbol for thesecond EPDCCH is the OFDM symbol at which an initial signal has beendetected or that is the OFDM symbol prescribed number of OFDM symbolsafter the OFDM symbol at which the initial signal has been detected.Alternatively, for example, the starting symbol for the second EPDCCH isthe OFDM symbol for which multiple candidates are defined or configuredand is the OFDM symbol at which the initial signal has been detected andthe OFDM symbols subsequent to the OFDM symbol at which the initialsignal has been detected and closest thereto.

Moreover, as an example, the end symbol of the second EPDCCH isconfigured independently or commonly for the individual EPDCCH sets viaRRC signaling. For example, as the end symbol of the second EPDCCH, oneof OFDM symbols #0 to #6 in slot 0 and OFDM symbols #0 to #6 in slot 1is configured. Moreover, for example, as the end symbol of the secondEPDCCH, a prescribed number of candidates are predefined from among OFDMsymbols #0 to #6 in slot 0 and OFDM symbols #0 to #6 in slot 1, and anyone of the candidates is configured. Alternatively, for example, as theend symbol of the second EPDCCH, any of OFDM symbol #6 in slot 0 andOFDM symbol #6 in slot 1 is configured. Alternatively, for example, theend symbol of the second EPDCCH is determined based on the startingsymbol for the second EPDCCH in the burst. Alternatively, for example,the end symbol of the second EPDCCH is determined based on the startingsymbol for the second EPDCCH in the burst and the maximum length of theburst. Alternatively, for example, the end symbol of the second EPDCCHis determined based on control information included in the initialsignal in the burst. Specifically, the control information includesinformation indicating the end symbol of the second EPDCCH.Alternatively, for example, the end symbol of the second EPDCCH isdetermined based on control information included in a prescribed channeland/or signal transmitted at the partial subframe.

The terminal device monitors a set of EPDCCH candidates in one or moreeffective Serving cells for configuration of the control information viahigher layer signaling. Here, monitoring (to monitor) implicitlyindicates that decode of each of the EPDCCHs in each of the sets ofEPDCCH candidates is attempted according to DCI format for monitoring.Sets of EPDCCH candidates to be monitored are defined in UE-specificSearch Space (USS) of the EPDCCH. Here, the USS is a logical areaconfigured in a UE-specific manner and is an area that can be used fortransmitting downlink control information. Monitoring is also referredto as blind detection.

Moreover, the starting symbol for the second EPDCCH and/or the endsymbol of the second EPDCCH may be blind-detected (monitored) amongmultiple OFDM symbol candidates by a terminal. For example, multiplecandidates are defined or configured for the starting symbol for thesecond EPDCCH and/or the end symbol of the second EPDCCH, and theterminal monitors the second EPDCCH presumed to be transmitted based onthe OFDM symbols defined or configured as the candidates. In otherwords, the presumed starting symbols and/or end symbols may beindependent (different) from each other among the individual secondEPDCCHs in the set of the second EPDCCH candidates.

A subframe at which the UE monitors the EPDCCH USS is configured foreach Serving cell by a higher layer. More specifically, in a subframethat is not a subframe at which uplink transmission for an FDD halfduplex terminal device is requested and that is not part of ameasurement gap in an active time (a period that is not a non-activetimer operating period in discontinuous reception, a period that is nota non-reception period, and the total period in which the terminaldevice is operating), the higher layer configures monitoring of theEPDCCH. Here, discontinuous reception is an operation in which theterminal device need not be activated (active state) (may be non-active)for optimization of buttery consumption of the terminal device exceptfor part of the period. The Frequency Division Duplex (FDD) half duplexterminal device is a terminal device that does not have the function ofperforming uplink transmission and downlink reception simultaneously (inthe same subframe) in an FDD band. Moreover, the measurement gap is aperiod in which transmission/reception is stopped in the Serving cell toperform measurement for mobility (handover) (received power measurementfor a cell other than the Serving cell), and a measurement gap patternis configured by the RRC.

The terminal device does not monitor the EPDCCH in (e1) to (e4) below.

(e1) In the case of a special subframe with special subframeconfiguration 0 and 5 in the TDD and a normal downlink CP (a specialsubframe having fewer than six OFDM symbols in the DwPTS).

(e2) In the case of a special subframe with special subframeconfiguration 0, 4, and 7 in the TDD and an extended downlink CP (aspecial subframe having fewer than six OFDM symbols in the DwPTS).

(e3) In the case of a subframe at which decode of a Physical MulticastChannel (PMCH) is indicated by a higher layer.

(e4) In the case where different UL/DL configurations are configured forthe TDD and a Primary cell and for a Secondary cell, the case of adownlink subframe in the Secondary cell, where the same subframe in thePrimary cell is a special subframe, and the case where the terminaldevice does not have the capability of performing simultaneoustransmission and reception in the Primary cell and the Secondary cell.

Here, the special subframe is a subframe including three sections, asection in which downlink transmission is performed (DwPTS), a guardperiod (GP), and a section in which uplink transmission is performed(UpPTS) in this order in one subframe, and the lengths of the DwPTS, theGP, and the UpPTS are uniquely determined based on the special subframeconfiguration and the CP length. The PMCH is a channel for providingMultimedia Broadcast/Multicast Service (MBMS) service and is mapped onlyto MBSFN subframes.

Note that any of the following 10 configurations is configured for thespecial subframe configuration.

In special subframe configuration 0, the DwPTS is 6592 samples in anormal downlink CP, and the UpPTS is 2192 samples in a normal uplink CPand 2560 samples in an extended uplink CP. In contrast, the DwPTS is7680 samples in an extended downlink CP, and the UpPTS is 2192 samplesin a normal uplink CP and 2560 samples in an extended uplink CP. TheDwPTS is constituted of three OFDM symbols, and the UpPTS is constitutedof one SC-FDMA symbol.

In special subframe configuration 1, the DwPTS is 19760 samples in anormal downlink CP, and the UpPTS is 2192 samples in a normal uplink CPand 2560 samples in an extended uplink CP. In contrast, the DwPTS is20480 samples in an extended downlink CP, and the UpPTS is 2192 samplesin a normal uplink CP and 2560 samples in an extended uplink CP. TheDwPTS is constituted of nine OFDM symbols in the case of a normaldownlink CP and eight OFDM symbols in the case of an extended downlinkCP, and the UpPTS is constituted of one SC-FDMA symbol.

In special subframe configuration 2, the DwPTS is 21952 samples in anormal downlink CP, and the UpPTS is 2192 samples in a normal uplink CPand 2560 samples in an extended uplink CP. In contrast, the DwPTS is23040 samples in an extended downlink CP, and the UpPTS is 2192 samplesin a normal uplink CP and 2560 samples in an extended uplink CP. TheDwPTS is constituted of 10 OFDM symbols in the case of a normal downlinkCP and nine OFDM symbols in the case of an extended downlink CP, and theUpPTS is constituted of one SC-FDMA symbol.

In special subframe configuration 3, the DwPTS is 24144 samples in anormal downlink CP, and the UpPTS is 2192 samples in a normal uplink CPand 2560 samples in an extended uplink CP. In contrast, the DwPTS is25600 samples in an extended downlink CP, and the UpPTS is 2192 samplesin a normal uplink CP and 2560 samples in an extended uplink CP. TheDwPTS is constituted of 11 OFDM symbols in the case of a normal downlinkCP and 10 OFDM symbols in the case of an extended downlink CP, and theUpPTS is constituted of one SC-FDMA symbol.

In special subframe configuration 4, the DwPTS is 26336 samples in anormal downlink CP, and the UpPTS is 2192 samples in a normal uplink CPand 2560 samples in an extended uplink CP. In contrast, the DwPTS is7680 samples in an extended downlink CP, and the UpPTS is 4384 samplesin a normal uplink CP and 5120 samples in an extended uplink CP. TheDwPTS is constituted of 12 OFDM symbols in the case of a normal downlinkCP and three OFDM symbols in the case of an extended downlink CP, andthe UpPTS is constituted of one SC-FDMA symbol in the case of a normaldownlink CP and two SC-FDMA symbols in an extended downlink CP.

In special subframe configuration 5, the DwPTS is 6592 samples in anormal downlink CP, and the UpPTS is 4384 samples in a normal uplink CPand 5120 samples in an extended uplink CP. In contrast, the DwPTS is20480 samples in an extended downlink CP, and the UpPTS is 4384 samplesin a normal uplink CP and 5120 samples in an extended uplink CP. TheDwPTS is constituted of three OFDM symbols in the case of a normaldownlink CP and eight OFDM symbols in the case of an extended downlinkCP, and the UpPTS is constituted of two SC-FDMA symbols.

In special subframe configuration 6, the DwPTS is 19760 samples in anormal downlink CP, and the UpPTS is 4384 samples in a normal uplink CPand 5120 samples in an extended uplink CP. In contrast, the DwPTS is23040 samples in an extended downlink CP, and the UpPTS is 4384 samplesin a normal uplink CP and 5120 samples in an extended uplink CP. TheDwPTS is constituted of nine OFDM symbols, and the UpPTS is constitutedof two SC-FDMA symbols.

In special subframe configuration 7, the DwPTS is 21952 samples in anormal downlink CP, and the UpPTS is 4384 samples in a normal uplink CPand 5120 samples in an extended uplink CP. In contrast, the DwPTS is12800 samples in an extended downlink CP, and the UpPTS is 4384 samplesin a normal uplink CP and 5120 samples in an extended uplink CP. TheDwPTS is constituted of 10 OFDM symbols in the case of a normal downlinkCP and five OFDM symbols in the case of an extended downlink CP, and theUpPTS is constituted of two SC-FDMA symbols.

In special subframe configuration 8, the DwPTS is 24144 samples in anormal downlink CP, and the UpPTS is 4384 samples in a normal uplink CPand 5120 samples in an extended uplink CP. The DwPTS is constituted of11 OFDM symbols in the case of a normal downlink CP, and the UpPTS isconstituted of two SC-FDMA symbols.

In special subframe configuration 9, the DwPTS is 13168 samples in anormal downlink CP, and the UpPTS is 4384 samples in a normal uplink CPand 5120 samples in an extended uplink CP. The DwPTS is constituted ofsix OFDM symbols in the case of a normal downlink CP, and the UpPTS isconstituted of two SC-FDMA symbols.

Here, in a case that the UpPTS is constituted of one SC-FDMA symbols,the terminal device can transmit a Sounding Reference Signal (SRS),which is a Reference Signal for uplink sounding, by using the oneSC-FDMA symbols in response to a request from a base station device. Ina case that the UpPTS is constituted of two SC-FDM symbols, the terminaldevice can transmit an SRS by using at least one of the two SC-FDMAsymbols in response to a request from a base station device.

Here, in a normal CP, a normal downlink subframe is constituted of 14OFDM symbols, and a normal uplink subframe is constituted of 14 SC-FDMAsymbols. Moreover, in an extended CP, a normal downlink subframe isconstituted of 12 OFDM symbols, and a normal uplink subframe isconstituted of 12 SC-FDMA symbols.

Note that any of the following seven configurations is configured forthe UL/DL configuration.

In UL/DL configuration 0, subframe 0 to subframe 9 in one radio frame(10 subframes) are a downlink subframe, a special subframe, an uplinksubframe, an uplink subframe, an uplink subframe, a downlink subframe, aspecial subframe, an uplink subframe, an uplink subframe, and an uplinksubframe in this order. The cycle of the point of transition fromdownlink to uplink corresponds to five subframes (5 ms).

In UL/DL configuration 1, subframe 0 to subframe 9 in one radio frameare a downlink subframe, a special subframe, an uplink subframe, anuplink subframe, a downlink subframe, a downlink subframe, a specialsubframe, an uplink subframe, an uplink subframe, and a downlinksubframe in this order. The cycle of the point of transition fromdownlink to uplink corresponds to five sub frames.

In UL/DL configuration 2, subframe 0 to subframe 9 in one radio frameare a downlink subframe, a special subframe, an uplink subframe, adownlink subframe, a downlink subframe, a downlink subframe, a specialsubframe, an uplink subframe, a downlink subframe, and a downlinksubframe in this order. The cycle of the point of transition fromdownlink to uplink corresponds to five subframes.

In UL/DL configuration 3, subframe 0 to subframe 9 in one radio frameare a downlink subframe, a special subframe, an uplink subframe, anuplink subframe, an uplink subframe, a downlink subframe, a downlinksubframe, a downlink subframe, a downlink subframe, and a downlinksubframe in this order. The cycle of the point of transition fromdownlink to uplink corresponds to 10 subframes (10 ms).

In UL/DL configuration 4, subframe 0 to subframe 9 in one radio frameare a downlink subframe, a special subframe, an uplink subframe, anuplink subframe, a downlink subframe, a downlink subframe, a downlinksubframe, a downlink subframe, a downlink subframe, and a downlinksubframe in this order. The cycle of the point of transition fromdownlink to uplink corresponds to 10 subframes.

In UL/DL configuration 5, subframe 0 to subframe 9 in one radio frameare a downlink subframe, a special subframe, an uplink subframe, adownlink subframe, a downlink subframe, a downlink subframe, a downlinksubframe, a downlink subframe, a downlink subframe, and a downlinksubframe in this order. The cycle of the point of transition fromdownlink to uplink corresponds to 10 subframes.

In UL/DL configuration 6, subframe 0 to subframe 9 in one radio frameare a downlink subframe, a special subframe, an uplink subframe, anuplink subframe, an uplink subframe, a downlink subframe, a specialsubframe, an uplink subframe, an uplink subframe, and a downlinksubframe in this order. The cycle of the point of transition fromdownlink to uplink corresponds to five subframes.

Here, in a case that the UL-DL configuration for at least one Servingcell is UL/DL configuration 5, not more than two Serving cells areconfigured.

ES^((L)) _(k), which is the USS in an EPDCCH in aggregation level L, isdefined by a set of EPDCCH candidates. Here, L takes any of 1, 2, 4, 8,16, and 32. For one EPDCCH-PRB set p, the ECCE corresponding to EPDCCHcandidate m in search space ES^((L)) _(k) is given based onL((Y_(p,k)+floor(mN_(ECCE,p,k)/(LM^((L)) _(p)))+b) mod(floor(N_(ECCE,p,k)/L)))+i. Here, i=0, . . . , L−1. Moreover, in a casethat a Carrier Indicator Field (CIF) is configured for the Serving cellfor which EPDCCHs are monitored, b indicates a CIF value, and otherwise,b=0. Additionally, m=0, 1, . . . , M^((L)) _(p)−1. In a case that no CIFis configured for the Serving cell for which EPDCCHs are monitored,M^((L)) _(p) represents the number of EPDCCHs to be monitored inaggregation level L in the EPDCCH-PRB set p in the Serving cell forwhich EPDCCHs are monitored. In other cases, M^((L)) _(p) represents thenumber of EPDCCHs to be monitored in aggregation level L in theEPDCCH-PRB set p in the Serving cell indicated by the CIF value. Here,the CIF is a field in a DCI format, and the CIF value is used todetermine the Serving cell to which the DCI format corresponds in PDSCHtransmission, PUSCH transmission, or a random access procedure of theServing cell and takes the same value as the Serving cell indexcorresponding to the Primary cell or the Secondary cell.

In a case that the ECCE corresponding to a certain EPDCCH candidate ismapped to a PRB pair overlapping with transmission of any of the PBCH, aprimary synchronization signal, and a secondary synchronization signalon the frequency, in the same subframe, the terminal device does notmonitor the EPDCCH candidate.

In a case that n^(EPDCCH) _(ID,i) of the same value is configured fortwo EPDCCH-PRB sets for a terminal device, and it is configured for theterminal device to receive the EPDCCH candidate that is an EPDCCHcandidate of a certain DCI payload size corresponding to one of theEPDCCH-PRB sets and that is mapped to a certain set of REs and for theterminal device to monitor the EPDCCH candidate that is an EPDCCHcandidate of the same DCI payload size corresponding to the otherEPDCCH-PRB set and that is mapped to the same set of REs, and further ina case that the first ECCE number in the received EPDCCH is used todetermine PUCCH resources for HARQ-ACK transmission, the first ECCEnumber is determined based on the EPDCCH-PRB set corresponding to p=0.Here, n^(PDCCH) _(ID,i) is a parameter used for initialization ofpseudo-random sequence generation of a Demodulation Reference Signal(DMRS) associated with the EPDCCH and is configured by a higher layer.Note that i takes a value 0 or 1 to indicate the EPDCCH set to which theEPDCCH associated with the DMRS belongs. In other words, i issubstantially synonymous with p.

Y_(p,k) is defined by Y_(p,k)=(A_(p)Y_(p,k-1)) mod D. Here, Y_(p,-1)represents the value of an RNTI, which is an identifier configured forthe terminal device in a physical layer, A₀ indicates 39827, A₁indicates 39829, D indicates 65537, and k=floor(n_(s)/2). In otherwords, since each subframe is constituted of two slots, k represents asubframe number in the radio subframe.

Moreover, the correspondence of the number of PRBs included in anEPDCCH-PRB set, an aggregation level, and the number of EPDCCHcandidates to be monitored can be defined. The aggregation leveldefining a search space and the number of EPDCCH candidates to bemonitored are given as follows. Here, N^(Xp) _(RB) represents the numberof PRB pairs constituting the EPDCCH-PRB set p.

Here, the aggregation level that defines a search space and the numberof EPDCCH candidates to be monitored can be independently defined for(1) the case where only one EPDCCH-PRB for distributed transmission isconfigured for the terminal device, (2) the case where only oneEPDCCH-PRB for localized transmission is configured for the terminaldevice, (3) the case where two EPDCCH-PRBs are configured fordistributed transmission for the terminal device, (4) the case where twoEPDCCH-PRBs for localized transmission are configured for the terminaldevice, and (5) the case where one EPDCCH-PRB for distributedtransmission and one EPDCCH-PRB for localized transmission areconfigured for the terminal device.

Note that, in the present embodiment, p1 is a reference sign identifyinga localized EPDCCH-PRB set, p1 is a reference sign identifying alocalized EPDCCH-PRB set, and p2 is a reference sign identifying adistributed EPDCCH-PRB set. In other words, N^(Xp1) _(RB) represents thenumber of PRB pairs constituting a localized EPDCCH-PRB set, and N^(Xp2)_(RB) represents the number of PRB pairs constituting a distributedEPDCCH-PRB set. Moreover, M^((L)) _(p1) represents the number of EPDCCHsin a localized EPDCCH-PRB set to be monitored in aggregation level L,and M^((L)) _(p2) represents the number of EPDCCHs in a distributedEPDCCH-PRB set to be monitored in aggregation level L.

To the correspondence of the number of PRBs included in an EPDCCH-PRBset, an aggregation level, and the number of EPDCCH candidates to bemonitored, case 1 is applied in cases of (c1) to (c4) below, case 2 isapplied in cases of (c5) to (c7) below, and case 3 is applied in a caseof (c8) below.

(c1) In the case of a normal subframe and a normal downlink CP, whereany of DCI formats 2, 2A, 2B, 2C, and 2D is monitored, and where M^(DL)_(RB) is 25 or greater. In other words, this is the case where thenumber of REs that can be used for EPDCCH transmission in one PRB pairis relatively large and the payload size of the DCI format issignificantly large.

(c2) In the case of a special subframe with special subframeconfiguration 3, 4, or 8 and a normal downlink CP (which means a specialsubframe in which a DwPTS is constituted of 11 or greater OFDM symbols),where any of DCI formats 2, 2A, 2B, 2C, and 2D is monitored, and whereM^(DL) _(RB) is 25 or greater. In other words, this is the case wherethe number of REs that can be used for EPDCCH transmission in one PRBpair is relatively large and the payload size of the DCI format issignificantly large.

(c3) In the case of a normal subframe and a normal downlink CP, whereany of DCI formats 1A, 1B, 1D, 1, 2, 2A, 2B, 2C, 2D, 0 and 4 ismonitored, and where n_(EPDCCH) is less than 104. In other words, thisis the case where the number of REs that can be used for EPDCCHtransmission in one PRB pair is significantly small.

(c4) In the case of a special subframe with special subframeconfiguration 3, 4, or 8 and a normal downlink CP (which means a specialsubframe in which a DwPTS is constituted of 11 or greater OFDM symbols),where any of DCI formats 1A, 1B, 1D, 1, 2, 2A, 2B, 2C, 2D, 0, and 4 ismonitored, and where n_(EPDCCH) is less than 104. In other words, thisis the case where the number of REs that can be used for EPDCCHtransmission in one PRB pair is significantly small.

(c5) In the case of a normal subframe and an extended downlink CP, andwhere any of DCI formats 1A, 1B, 1D, 1, 2, 2A, 2B, 2C, 2D, 0, and 4 ismonitored. In other words, this is the case where the number of REs thatcan be used for EPDCCH transmission in one PRB pair is relatively small.

(c6) In the case of a special subframe with special subframeconfiguration 1, 2, 6, 7, and 9 and a normal downlink CP (which means aspecial subframe in which a DwPTS is constituted of 6 or greater and 10or fewer OFDM symbols) and where any of DCI formats 1A, 1B, 1D, 1, 2,2A, 2B, 2C, 2D, 0, and 4 is monitored. In other words, this is the casewhere the number of REs that can be used for EPDCCH transmission in onePRB pair is relatively small.

(c7) In the case of a special subframe with special subframeconfiguration 1, 2, 3, 5, or 6 and an enhanced downlink CP (which meansa special subframe in which a DwPTS is constituted of 6 or greater and10 or fewer OFDM symbols) and where any of DCI formats 1A, 1B, 1D, 1, 2,2A, 2B, 2C, 2D, 0, and 4 is monitored. In other words, this is the casewhere the number of REs that can be used for EPDCCH transmission in onePRB pair is relatively small.

(c8) In the case other than any of (c1) to (c7) above. In other words,this is the case where the number of REs that can be used for EPDCCHtransmission in one PRB pair is relatively large and the payload size ofthe DCI format is not so large.

Here, in a case that no CIF is configured for the terminal device forthe Serving cell for which EPDCCHs are monitored, M^(DL) _(RB)corresponds to N^(DL) _(RB) of the Serving cell for which EPDCCHs aremonitored. In a case that a CIF is configured for the terminal devicefor the Serving cell for which EPDCCHs are monitored, M^(DL) _(RB)corresponds to N^(DL) _(RB) of the Serving cell indicated by a CIFvalue. Here, N^(DL) _(RB) represents a downlink bandwidth configurationand is expressed in a unit of a multiple of frequency direction resourceblock size. In other words, N^(DL) _(RB) represents the total number ofresource blocks in the frequency direction in a downlink componentcarrier in the Serving cell. Moreover, DCI formats 1A, 1B, 2D, and 1 areDCI formats used in a transmission mode in which one transport block canbe transmitted using one PDSCH and are used in respective PDSCHtransmission methods that are transmission diversity, closed loopspatial multiplexing using a single port, multi-user Multiple InputMultiple Output (MIMO), and single antenna port transmission. Moreover,DCI formats 2, 2A, 2B, 2C, and 2D are DCI formats used in a transmissionmode in which up to two transport blocks can be transmitted using onePDSCH and are used in respective PDSCH transmission methods that areclosed loop spatial multiplexing, large delay Cyclic Delay Diversity(CDD), 2-layer transmission, 8 or fewer layer transmission, and 8 orfewer layer transmission. In addition, DCI formats 2 and 2A are alsoused in a PDSCH transmission method based on transmission diversity, andDCI formats 2B, 2C, and 2D are also used in a PDSCH transmission methodusing a single antenna port. Moreover, DCI formats 0 and 4 are DCIformats used in respective transmission modes in which one and up to twotransport blocks can be transmitted using one PUSCH and are used inrespective PDSCH transmission methods that are single antenna porttransmission and closed loop spatial multiplexing.

The transmission mode is a mode semi-statically configured for theterminal device to receive PDSCH data transmission signaled using aPDCCH or an EPDCCH via higher layer signaling. Any of transmission mode1 to transmission mode 10 below is configured for the transmission mode.

In transmission mode 1, a PDSCH transmission method based on singleantenna port transmission (transmission using antenna port 0) is used,and DCI format 1 or 1A is used.

In transmission mode 2, a PDSCH transmission method based ontransmission diversity is used, and DCI format 1 or 1A is used.

In transmission mode 3, a PDSCH transmission method based on large delayCDD or transmission diversity is used, and DCI format 1 or 2A is used.

In transmission mode 4, a PDSCH transmission method based on closed loopspatial multiplexing or transmission diversity is used, and DCI format 1or 2 is used.

In transmission mode 5, a PDSCH transmission method based on multi-userMIMO or transmission diversity is used, and DCI format 1 or 1D is used.

In transmission mode 6, a PDSCH transmission method based on closed loopspatial multiplexing using a single port or transmission diversity isused, and DCI format 1 or 1B is used.

In transmission mode 7, a PDSCH transmission method based on any ofsingle antenna port transmission (transmission using antenna port 5),transmission diversity, and single antenna port transmission(transmission using antenna port 0) is used, and DCI format 1 or 1 isused.

In transmission mode 8, a PDSCH transmission method based on any oftwo-layer transmission (transmission using antenna port 7 and antennaport 8), transmission diversity, and single antenna port transmission(transmission using antenna port 0) is used, and DCI format 1 or 2B isused.

In transmission mode 9, a PDSCH transmission method based on any of 8 orfewer layer transmission (transmission using antenna port 7 to antennaport 14), transmission diversity, and single antenna port transmission(transmission using antenna port 0) (here, single antenna porttransmission using antenna port 7 in the case of an MBSFN subframe) isused, and DCI format 1 or 2C is used.

In transmission mode 10, a PDSCH transmission method based on any of 8or fewer layer transmission (transmission using antenna port 7 toantenna port 14), transmission diversity, and single antenna porttransmission (transmission using antenna port 0) (here, single antennaport transmission using antenna port 7 in the case of an MBSFN subframe)is used, and DCI format 1 or 2C is used.

Note that transmission modes other than the above (e.g., transmissionmode 11 defined similarly to transmission modes 9 and 10, or the like)may be used. For example, in transmission mode 11, a DCI format used ina LAA cell is used. In transmission mode 11, a processing method, acoding method, a transmission method, and/or a reception method in a LAAcell described in the present embodiment is used.

In a case that no CIF is configured for the terminal device, theterminal device monitors the USS of one EPDCCH in each of aggregationlevels given based on correspondence tables in FIG. X1 to FIG. X10, ineach of activated Serving cells for which monitoring of EPDCCHs isconfigured. In a case that EPDCCH monitoring is configured for theterminal device, and a CIF is configured for the terminal device, theterminal device monitors the USS of one or more EPDCCHs in each ofaggregation levels given based on the correspondence tables in FIG. X1to FIG. X10, in each of one or more activated Serving cells asconfigured via higher layer signaling. The terminal device for which aCIF associated with EPDCCH monitoring in Serving cell c is configured,monitors EPDCCHs for which a CIF is configured and to which a CRCscrambled with a C-RNTI is attached, in the USSs in the EPDCCHs inServing cell c. The terminal device for which a CIF associated withEPDCCH monitoring in the Primary cell is configured, monitors EPDCCHsfor which a CIF is configured and to which a CRC scrambled with a SemiPersistent Scheduling-RNTI (SPS-RNTI) is attached, in the USS in theEPDCCH in the Primary cell. Here, the C-RNTI is an RNTI used for dynamicPDSCH transmission or EPDCCH transmission associated with PUSCHtransmission, and the SPS-RNTI is an RNTI used for semi-stationary PDSCHtransmission or EPDCCH transmission associated with PUSCH transmission.

In the Serving cell for which EPDCCHs are monitored, in a case that noCIF is configured for the terminal device, the terminal device monitorsthe USSs in the EPDCCHs for the EPDCCHs including no CIF, and in a casethat a CIF is configured for the terminal device, the terminal devicemonitors the USSs in the EPDCCHs for the EPDCCHs including the CIF. Inother words, whether to decode an EPDCCH as an EPDCCH including a CIF ordecode the EPDCCH as an EPDCCH including no CIF, is determined dependingon whether a CIF is configured. In a case that the terminal device isconfigured to monitor EPDCCHs including the CIF corresponding to theSecondary cell, in a different Serving cell, the terminal differencedoes not monitor EPDCCHs in the Secondary cell. In the Serving cell forwhich EPDCCHs are monitored, the terminal device monitors EPDCCHcandidates at least for the same Serving cell.

The terminal device configured to monitor EPDCCH candidates to which aCRC scrambled with a C-RNTI in a DCI format size including a CIF, on acertain Serving cell, is attached, presumes that the EPDCCH candidatesin the DCI format size may be transmitted in USSs in various EPDCCHscorresponding to various values that the CIF can take in the DCI formatsize, in the Serving cell.

In a case that an opportunity for transmission of a positioningReference Signal is configured only at an MBSFN subframe for the Servingcell for which EPDCCHs are monitored, and the CP length used in subframe0 is of a normal CP, the terminal device is not requested to monitorEPDCCHs at a subframe configured by a higher layer as being part of theopportunity for the transmission of the positioning Reference Signal.

The terminal device presumes that the same C_(init) value is used forantenna ports 107 and 108 during the monitoring of EPDCCH candidatesassociated with any of antenna ports 107 and 108. The terminal devicepresumes that the same C_(init) value is used for antenna ports 109 and110 during the monitoring of EPDCCH candidates associated with any ofantenna ports 109 and 110.

In a case that the terminal device is configured to receive PDSCH datatransmission according to transmission modes 1 to 9 via higher layersignaling for a certain Serving cell, the terminal device follows (s1)and (s2) below.

(s1) In a case that epdcch-StartSymbol-r11, which is a higher layerparameter, is configured for the terminal device, the start ODFM symbolfor an EPDCCH given by 1_(EPDCCHStart), which is an index in the firstslot in one subframe, (the first OFDM symbol to which an EPDCCH ismapped in one subframe, also referred to as an EPDCCH start position) isdetermined based on the higher layer parameter. Here, the higher layerparameter epdcch-StartSymbol-r11 is a parameter that can be individuallyconfigured for each of the EPDCCH sets and a parameter for specifyingthe start OFDM symbol in the EPDCCH (information indicating the startOFDM symbol). The higher layer parameter epdcch-StartSymbol-r11 isconfigured by using an RRC message.

(s2) In other cases, the start OFDM symbol for an EPDCCH given by1_(EPDCCHStart), which is an index in the first slot in one subframe, isgiven by a Control Format Indicator (CFI) value in the subframe in theServing cell in a case that N^(DL) _(RB) is greater than 10, and isgiven by adding one to the CFI value of the subframe in the Serving cellin a case that N^(DL) _(RB) is 10 or less. Here, the CFI is a parametertaking any of 1, 2, and 3 as a value and is control informationtransmitted/received via a Physical CFI Channel (PCFICH). The CFI isinformation on the number of OFDM symbols to be used for PDCCHtransmission in one subframe.

In a case that the terminal device is configured to receive datatransmission on a PDSCH in transmission mode 10 via higher layersignaling for a Serving cell, the start OFDM symbol for EPDCCHmonitoring in subframe k follows the higher layer parameterpdsch-Start-r11 for each EPDCCĤPRB set as in (s3) to (s6) below. Here,the higher layer parameter pdsch-Start-r11 is a parameter that can beconfigured for each of four kinds of parameter sets for a PDSCH and is aparameter for specifying the start OFDM symbol of a PDSCH (informationindicating the start OFDM symbol). The higher layer parameterepdcch-Start-r11 is configured by using an RRC message.

(s3) In a case that the pdsch-Start-r11 value belongs to the set of 1,2, 3, and 4 (the value is any of 1, 2, 3, and 4), 1′_(EPDCCHStart) isgiven by pdsch-Start-r11.

(s4) In other cases (in a case that the pdsch-Start-r11 value does notbelong to the set of 1, 2, 3, and 4), 1′_(EPDCCHStart) is given by theCFI value in subframe k in the Serving cell in a case that N^(DL) _(RB)is greater than 10, and is given by adding one to the CFI value insubframe k in the Serving cell in a case that N^(DL) _(RB) is 10 orless.

(s5) In a case that subframe k is the subframe specified by the higherlayer parameter mbsfn-SubframeConfigList-r11, or in a case that subframek is subframe 1 or 6 in the TDD subframe configuration, 1_(EPDCCHStart)is given by 1_(EPDCCHStart)=min(2, 1′_(EPDCCHStart)).

(s6) In other cases (in a case that subframe k is not the subframespecified by the higher layer parameter mbsfn-SubframeConfigList-r11,and in a case that subframe k is not subframe 1 or 6 in the TDD subframeconfiguration), 1_(EPDCCHStart) is given by1_(EPDCCHStart)=1′_(EPDCCHStart).

In a case that the terminal device is configured to receive PDSCH datatransmission according to transmission modes 1 to 9 via higher layersignaling and to monitor EPDCCHs, for a certain Serving cell, theterminal device presumes that antenna ports 0 to 3 and 107 to 110 in theServing cell are quasi co-located for Doppler shift, Doppler spread,average delay, and delay spread (receives transmissions as beingtransmitted from the same transmission point, or receives transmissionsas being transmitted from different transmission points).

In a case that the terminal device is configured to receive PDSCH datatransmission according to transmission mode 10 via higher layersignaling, for a certain Serving cell and to monitor EPDCCHs, (q1) and(q1) below are applied to each EPDCCH-PRB set.

(q1) In a case that the terminal device is configured by a higher layerto decode PDSCHs based on quasi co-location type A, the terminal devicepresumes that antenna ports 0 to 3 and 107 to 110 in the Serving cellare quasi co-located for Doppler shift, Doppler spread, average delay,and delay spread.

(q2) In a case that the terminal device is configured by a higher layerto decode PDSCHs based on quasi co-location type B, the terminal devicepresumes that antenna ports 15 to 22 and 107 to 110 corresponding to thehigher layer parameter qcl-CSI-RS-ConfigNZPId-r11 are quasi co-locatedfor Doppler shift, Doppler spread, average delay, and delay spread.Here, the higher layer parameter qcl-CSI-RS-ConfigNZPId-r11 is aparameter that can be configured for each of four kinds of PDSCHparameter sets and is a parameter for specifying quasi co-location of aPDSCH (information indicating the CSIRS with which a UE-specificReference Signal associated with a PDSCH is quasi co-located). Thehigher layer parameter qcl-CSI-RS-ConfigNZPId-r11 is configured by usingan RRC message.

Here, quasi co-location type A and quasi co-location type B areparameters, one of which is configured for each Serving cell for theterminal device configured in transmission mode 10. Type A indicatesthat antenna ports 7 to 14 are quasi co-located with CRS antenna ports 0to 3 of the Serving cell, and type B indicates that antenna ports 7 to14 are quasi co-located with any of CSIRS antenna ports 15 to 22. Inother words, in a case that type B is configured, a CSIRS is notnecessarily transmitted from the base station device corresponding tothe Serving cell and may be transmitted from another base stationdevice. In this case, an EPDCCH and a PDSCH quasi co-located with theCSIRS are normally transmitted from the same transmission point as theCSIRS (for example, an overhang antenna device in a remote siteconnected to a base station device via backhaul, or another base stationdevice).

In a case that the terminal device is configured to receive PDSCH datatransmission according to transmission mode 10 via higher layersignaling and to monitor EPDCCHs for a certain Serving cell, theterminal device uses, for each EPDCCH-PRB set, a parameter specified bythe higher layer parameter MappingQCL-ConfigId-r11, for RE mapping ofthe EPDCCH and determination of antenna port quasi co-location. Theparameter set includes parameters (Q1) to (Q6) below for RE mapping ofan EPDCCH and determination for antenna port quasi co-location.

(Q1) crs-PortsCount-r11. crs-PortsCount-r11 is a parameter indicatingthe number of CRS ports to be used for mapping a PDSCH and an EPDCCH toREs.

(Q2) crs-FreqShift-r11. crs-FreqShift-r11 is a parameter indicating CRSfrequency shift to be used for mapping a PDSCH and an EPDCCH to REs.

(Q3) mbsdn-SubframeConfigList-r11. mbsdn-SubframeConfigList-r11 is aparameter indicating the position of an MBSFN subframe to be used formapping a PDSCH and an EPDCCH to REs. In a subframe configured as anMBSFN subframe based on the parameter, a PDSCH and an EPDCCH are mappedas a CRS existing only in OFDM symbols to which a PDCCH can be mapped(as no CRS existing in OFDM symbols to which a PDCCH is not to bemapped).

(Q4) csi-RS-ConfigZPId-r11. csi-RS-ConfigZPId-r11 is a parameterindicating the position of zero-power CSIRS to be used for mapping aPDSCH and an EPDCCH to REs.

(Q5) pdsch-Start-r11. pdsch-Start-r11 is a parameter indicating a startOFDM symbol to be used for mapping a PDSCH and an EPDCCH to REs.

(Q6) qcl-CSI-RS-ConfigNZPId-r11. qcl-CSI-RS-ConfigNZPId-r11 is aparameter indicating the CSIRS with which a Reference Signal fordemodulation of a PDSCH and an EPDCCH is co-located. This parameter canspecify the ID of any of one or more configured CSIRSs. The ReferenceSignal for demodulation of a PDSCH and an EPDCCH is assumed to be quasico-located with the CSIRS which ID is specified.

Next, a PDSCH to be scheduled by a second EPDCCH will be described. Anexample of the PDSCH to be scheduled by the second EPDCCH includes onlya PDSCH mapped to a subframe at which the second EPDCCH has beendetected (mapped).

Another example of the PDSCH to be scheduled by the second EPDCCHincludes a PDSCH mapped to any of the subframes in the burst includingthe subframe at which the second EPDCCH has been detected (mapped).Information (configuration) on the subframe to which the PDSCH is mappedmay be configured using RRC or may be notified using DCI transmitted onthe second EPDCCH. Moreover, the PDSCH scheduled by the second EPDCCHmay be mapped to one subframe or multiple subframes.

Next, description will be given of the starting symbol and/or an endsymbol of a PDSCH in a case that the PDSCH scheduled by the secondEPDCCH is mapped to a partial subframe. For example, the starting symboland/or the end symbol of the PDSCH is determined based on the controlinformation included in the DCI in the second EPDCCH for scheduling.Alternatively, for example, the starting symbol and/or the end symbol ofthe PDSCH is determined based on the starting symbol and/or the endsymbol of the second EPDCCH for scheduling. Alternatively, for example,the starting symbol and/or the end symbol of the PDSCH is the same asthe starting symbol and/or the end symbol of the second EPDCCH forscheduling. Alternatively, for example, the starting symbol and/or theend symbol of the PDSCH is an OFDM symbol calculated based on thestarting symbol and/or the end symbol of the second EPDCCH forscheduling. Alternatively, for example, the starting symbol and/or theend symbol of the PDSCH is configured independently of the startingsymbol and/or the end symbol of the second EPDCCH for scheduling via RRCsignaling. Alternatively, for example, the starting symbol and/or theend symbol of the PDSCH is determined based on the control informationincluded in a physical channel or a physical signal mapped to thesubframe. Moreover, different determination methods or differentnotification methods may be used for the starting symbol and the endsymbol of the PDSCH.

Moreover, the configuration for a subframe at which the first EPDCCH inthe first EPDCCH set is monitored and the configuration for a subframeat which the second EPDCCH in the second EPDCCH set is monitored may bedifferent from each other. For example, the subframe at which the firstEPDCCH is monitored is configured commonly for the entire first EPDCCHset, and whether to perform monitoring is configured for each subframeby using bitmap-format information. As an example, the configuration forthe subframe at which the second EPDCCH is monitored is the same as butis configured independently of the configuration for the subframe atwhich the first EPDCCH is monitored. Another example of theconfiguration for the subframe at which the second EPDCCH is monitoredis to monitor the second EPDCCH at a subframe at which the terminal hasdetected burst in a LAA cell (downlink burst transmission).

Part of the above-described embodiment can be stated differently asfollows.

The terminal device according to the present embodiment includes: ahigher layer processing unit configured to configure a first EPDCCH setfor monitoring a first EPDCCH in a first Serving cell and a secondEPDCCH set for monitoring a second EPDCCH in a second Serving cell; anda reception unit configured to monitor the first EPDCCH and the secondEPDCCH. In a certain subframe, a starting symbol for the first EPDCCHand a starting symbol for the second EPDCCH are determinedindependently.

The base station device according to the present embodiment includes: ahigher layer processing unit configured to configure, for a terminaldevice, a first EPDCCH set for monitoring a first EPDCCH in a firstServing cell and a second EPDCCH set for monitoring a second EPDCCH in asecond Serving cell; and a transmission unit configured to transmit thefirst EPDCCH and the second EPDCCH. In a certain subframe, a startingsymbol for the first EPDCCH and a starting symbol for the second EPDCCHare determined independently.

The maximum value that can be configured for the starting symbol for thesecond EPDCCH is greater than the maximum value that can be configuredfor the starting symbol for the first EPDCCH. For example, a value thatcan be configured for the first EPDCCH starting symbol is 1, 2, 3, or 4.The values that can be configured for the starting symbol for the secondEPDCCH include a different value from the values that can be configuredfor the starting symbol for the first EPDCCH.

The starting symbol for the first EPDCCH is configured based on a higherlayer parameter. The starting symbol for the second EPDCCH is determinedbased on a symbol at which an initial signal has been detected. Forexample, the starting symbol for the second EPDCCH is the same as thesymbol at which the initial signal has been detected.

An end symbol of the first EPDCCH is the last symbol in a certainsubframe. An end symbol of the second EPDCCH is configured based on ahigher layer parameter.

The starting symbol and/or the end symbol of the PDSCH to be scheduledby the second EPDCCH is determined based on the starting symbol and/orthe end symbol of the second EPDCCH.

The starting symbol and/or the end symbol of the PDSCH to be scheduledby the second EPDCCH is determined based on the DCI in the secondEPDCCH.

The terminal device according to the present embodiment includes: ahigher layer processing unit configured to configure a first EPDCCH setfor monitoring a first EPDCCH in a first Serving cell and a secondEPDCCH set for monitoring a second EPDCCH in a second Serving cell; anda reception unit configured to monitor the first EPDCCH and the secondEPDCCH. In each physical resource block pair, the EREGs used to definemapping of the first EPDCCH and the second EPDCCH to Resource Elementsare common to the first EPDCCH and the second EPDCCH. The number ofEREGs constituting each of the ECCEs used for transmission of the firstEPDCCH and the number of EREGs constituting each of the ECCEs fortransmission of the first EPDCCH are determined independently.

The base station device according to the present embodiment includes: ahigher layer processing unit configured to configure, for a terminaldevice, a first EPDCCH set for monitoring a first EPDCCH in a firstServing cell and a second EPDCCH set for monitoring a second EPDCCH in asecond Serving cell; and a transmission unit configured to transmit thefirst EPDCCH and the second EPDCCH. In each physical resource blockpair, the EREGs used to define mapping of the first EPDCCH and thesecond EPDCCH to Resource Elements are common to the first EPDCCH andthe second EPDCCH. The number of EREGs constituting each of the ECCEsused for transmission of the first EPDCCH and the number of EREGsconstituting each of the ECCEs for transmission of the first EPDCCH aredetermined independently.

The maximum value of the numbers of EREGs constituting each of the ECCEsused for transmission of the second EPDCCH is greater than the maximumvalue of the numbers of EREGs constituting each of the ECCEs fortransmission of the first EPDCCH. For example, the numbers of EREGsconstituting each of the ECCEs used for transmission of the first EPDCCHinclude 4 or 8. The numbers of EREGs constituting each of the ECCEs usedfor transmission of the second EPDCCH include a different number fromthe number of EREGs constituting each of the ECCEs for transmission ofthe first EPDCCH. The numbers of EREGs constituting each of the ECCEsused for transmission of the second EPDCCH include 4, 8 or 16.

Resource Elements to which a Demodulation Reference Signal associatedwith the second EPDCCH is to be mapped are determined based on thestarting symbol and/or the end symbol of the second EPDCCH.

The maximum value of the numbers of the physical resource block pairsused for the second EPDCCH set is greater than the maximum value of thenumbers of the physical resource block pairs used for the first EPDCCHset. For example, the numbers of physical resource block pairs used forthe first EPDCCH set include 2, 4, or 8. The numbers of the physicalresource block pairs used for the second EPDCCH set include a differentnumber from the numbers of the physical resource block pairs used forthe first EPDCCH set. The numbers include 2, 4, 8, or 16.

Moreover, although the description has been given in each of theabove-described embodiments by using the terms “Primary cell” and “PScell”, these terms need not always be used. For example, “Primary cell”in each of the above-described embodiments may be referred to as a“master cell”, and a “PS cell” in each of the above-describedembodiments may be referred to as a “Primary cell”.

A program running on each of the base station device 2 and the terminaldevice 1 according to the present invention may be a program (a programfor causing a computer to operate) that controls a Central ProcessingUnit (CPU) and the like in such a manner as to realize the functionsaccording to the above-described embodiments of the present invention.The information handled in these devices is temporarily stored in aRandom Access Memory (RAM) while being processed. Thereafter, theinformation is stored in various types of Read Only Memory (ROM) such asa flash ROM and a Hard Disk Drive (HDD), and when necessary, is read bythe CPU to be modified or rewritten.

Note that the terminal device 1 and the base station device 2-1 or thebase station device 2-2 according to the above-described embodiments maybe partially realized by the computer. In this case, this configurationmay be realized by recording a program for realizing such controlfunctions on a computer-readable recording medium and causing a computersystem to read the program recorded on the recording medium forexecution.

Note that the “computer system” here is defined as a computer systembuilt into the terminal device 1 or the base station device 2-1 or thebase station device 2-2, and the computer system includes an OS andhardware components such as peripheral devices. Furthermore, the“computer-readable recording medium” refers to a portable medium such asa flexible disk, a magneto-optical disk, a ROM, and a CD-ROM, and astorage device such as a hard disk built into the computer system.

Moreover, the “computer-readable recording medium” may include a mediumthat dynamically retains the program for a short period of time, such asa communication line that is used to transmit the program over a networksuch as the Internet or over a communication line such as a telephoneline, and a medium that retains, in that case, the program for a fixedperiod of time, such as a volatile memory within the computer systemwhich functions as a server or a client. Furthermore, the program may beconfigured to realize some of the functions described above, and alsomay be configured to be capable of realizing the functions describedabove in combination with a program already recorded in the computersystem.

Furthermore, the base station device 2-1 or base station device 2-2according to the above-described embodiments can be realized as anaggregation (a device group) constituted of multiple devices. Devicesconstituting the device group may be each equipped with some or allportions of each function or each functional block of the base stationdevice 2-1 or base station device 2-2 according to the above-describedembodiments. It is only required that the device group itself includegeneral functions or general functional blocks of the base stationdevice 2-1 or base station device 2-2. Furthermore, the terminal device1 according to the above-described embodiments can also communicate withthe base station device as the aggregation.

Furthermore, the base station device 2-1 or base station device 2-2according to the above-described embodiments may be an Evolved UniversalTerrestrial Radio Access Network (E-UTRAN). Furthermore, the basestation device 2-1 or base station device 2-2 according to theabove-described embodiments may have some or all portions of a functionof a higher node for an eNodeB.

Furthermore, some or all portions of each of the terminal device 1 andthe base station device 2-1 or base station device 2-2 according to theabove-described embodiments may be typically realized as a large-scaleintegration (LSI) that is an integrated circuit or may be realized as achip set. The functional blocks of each of the terminal device 1 and thebase station device 2-1 or base station device 2-2 may be individuallyrealized as a chip, or some or all of the functional blocks may beintegrated into a chip. Furthermore, a circuit integration technique isnot limited to the LSI, and may be realized with a dedicated circuit ora general-purpose processor. Furthermore, in a case where with advancesin semiconductor technology, a circuit integration technology with whichan LSI is replaced appears, it is also possible to use an integratedcircuit based on the technology.

Furthermore, according to the above-described embodiments, the cellularmobile station device is described as one example of a terminal deviceor a communication device, but the present invention is not limited tothis, and can be applied to a fixed-type electronic apparatus installedindoors or outdoors, or a stationary-type electronic apparatus, forexample, a terminal device or a communication device, such as anaudio-video (AV) apparatus, a kitchen apparatus, a cleaning or washingmachine, an air-conditioning apparatus, office equipment, a vendingmachine, and other household apparatuses.

The embodiments of the present invention have been described in detailabove referring to the drawings, but the specific configuration is notlimited to the embodiments and includes, for example, an amendment to adesign that falls within the scope that does not depart from the gist ofthe present invention. Furthermore, various modifications are possiblewithin the scope of the present invention defined by claims, andembodiments that are made by suitably combining technical meansdisclosed according to the different embodiments are also included inthe technical scope of the present invention. Furthermore, aconfiguration in which a constituent element that achieves the sameeffect is substituted for the one that is described according to theembodiments is also included in the technical scope of the presentinvention.

(1) A terminal device according to an aspect of the present embodimentis a terminal device configured to communicate with a base stationdevice and includes: a higher layer processing unit configured toconfigure a first EPDCCH set for monitoring a first EPDCCH in a firstServing cell and a second EPDCCH set for monitoring a second EPDCCH in asecond Serving cell; and a reception unit configured to monitor thefirst EPDCCH and the second EPDCCH. In a certain subframe, a startingsymbol for the first EPDCCH and a starting symbol for the second EPDCCHare determined independently.

(2) A terminal device according to an aspect of the present invention isthe above-described terminal device, in which the maximum value that canbe configured for the starting symbol for the second EPDCCH is greaterthan the maximum value that can be configured for the starting symbolfor the first EPDCCH.

(3) A terminal device according to an aspect of the present invention isthe above-described terminal device, in which the starting symbol forthe first EPDCCH is configured based on a higher layer parameter whilethe starting symbol for the second EPDCCH is determined based on asymbol at which an initial signal has been detected.

(4) A terminal device according to an aspect of the present invention isthe above-described terminal device, in which an end symbol of the firstEPDCCH is a last symbol in a certain subframe while an end symbol of thesecond EPDCCH is configured based on a higher layer parameter.

(5) A terminal device according to an aspect of the present invention isthe above-described terminal device, in which a starting symbol and/oran end symbol of a PDSCH to be scheduled by the second EPDCCH isdetermined based on the starting symbol and/or the end symbol of thesecond EPDCCH.

(6) A terminal device according to an aspect of the present invention isthe above-described terminal device, in which the starting symbol and/orthe end symbol of the PDSCH to be scheduled by the second EPDCCH isdetermined based on DCI in the second EPDCCH.

(7) A base station device according to an aspect of the presentembodiment is a base station device configured to communicate with aterminal device and includes: a higher layer processing unit configuredto configure a first EPDCCH set for monitoring a first EPDCCH in a firstServing cell and a second EPDCCH set for monitoring a second EPDCCH in asecond Serving cell, for the terminal device; and a transmission unitconfigured to transmit the first EPDCCH and the second EPDCCH. In acertain subframe, a starting symbol for the first EPDCCH and a startingsymbol for the second EPDCCH are determined independently.

(8) A base station device according to an aspect of the presentinvention is the above-described base station device, in which themaximum value that can be configured for the starting symbol for thesecond EPDCCH is greater than the maximum value that can be configuredfor the starting symbol for the first EPDCCH.

(9) A base station device according to an aspect of the presentinvention is the above-described base station device, in which thestarting symbol for the first EPDCCH is configured based on a higherlayer parameter while the starting symbol for the second EPDCCH isdetermined based on a symbol at which an initial signal has beendetected.

(10) A base station device according to an aspect of the presentinvention is the above-described base station device, in which an endsymbol of the first EPDCCH is a last symbol in a certain subframe whilean end symbol of the second EPDCCH is configured based on a higher layerparameter.

(11) A base station device according to an aspect of the presentinvention is the above-described base station device, in which astarting symbol and/or an end symbol of a PDSCH to be scheduled by thesecond EPDCCH is determined based on the starting symbol and/or the endsymbol of the second EPDCCH.

(12) A base station device according to an aspect of the presentinvention is the above-described base station device, in which thestarting symbol and/or the end symbol of the PDSCH to be scheduled bythe second EPDCCH is determined based on DCI in the second EPDCCH.

(13) A communication method according to an aspect of the presentembodiment is a communication method used by a terminal deviceconfigured to communicate with a base station device and includes thesteps of: configuring a first EPDCCH set for monitoring a first EPDCCHin a first Serving cell and a second EPDCCH set for monitoring a secondEPDCCH in a second Serving cell; and monitoring the first EPDCCH and thesecond EPDCCH. In a certain subframe, a starting symbol for the firstEPDCCH and a starting symbol for the second EPDCCH are determinedindependently.

(14) A communication method according to an aspect of the presentembodiment is a communication method used by a base station deviceconfigured to communicate with a terminal device and includes the stepsof: configuring a first EPDCCH set for monitoring a first EPDCCH in afirst Serving cell and a second EPDCCH set for monitoring a secondEPDCCH in a second Serving cell, for the terminal device; andtransmitting the first EPDCCH and the second EPDCCH. In a certainsubframe, a starting symbol for the first EPDCCH and a starting symbolfor the second EPDCCH are determined independently.

REFERENCE SIGNS LIST

-   501 Higher layer-   502 Control unit-   503 Codeword generation unit-   504 Downlink subframe generation unit-   505 Downlink Reference Signal generation unit-   506 OFDM signal transmission unit-   507 Transmit antenna-   508 Receive antenna-   509 SC-FDMA signal reception unit-   510 Uplink subframe processing unit-   511 Uplink control information extraction unit-   601 Receive antenna-   602 OFDM signal reception unit-   603 Downlink subframe processing unit-   604 Downlink Reference Signal extraction unit-   605 Transport block extraction unit-   606, 1006 Control unit-   607, 1007 Higher layer-   608 Channel state measurement unit-   609, 1009 Uplink subframe generation unit-   610 Uplink control information generation unit-   611, 612, 1011 SC-FDMA signal transmission unit-   613, 614, 1013 Transmit antenna

1. A terminal device (UE) comprising: a reception unit configured tomonitor multiple enhanced physical downlink control channels (EPDCCHs)on a Secondary cell, wherein in a case that the Secondary cell is alicensed assisted access Secondary cell and a higher layer parameter ofthe Secondary cell indicates that a starting position of downlinktransmission is either a Subframe boundary or a slot boundary, theterminal device is configured to monitor both a first set of UE-specificsearch space candidates in a first EPDCCH and a second set ofUE-specific search space candidates in a second EPDCCH, in a subframe, astarting symbol for the first EPDCCH is specified by an index in a firstslot in the subframe, and a starting symbol for the second EPDCCH isspecified by the index in a second slot in the subframe.
 2. The terminaldevice according to claim 1, wherein a demodulation reference signal(DMRS) associated with the first EPDCCH is transmitted in both the firstslot and the second slot, and a DMRS associated with the second EPDCCHis transmitted only in the second slot.
 3. The terminal device accordingto claim 1, wherein a first set of numbers of enhanced control channelelements (ECCEs) or a second set of numbers of ECCEs is used for thefirst EPDCCH, only the first set of the numbers of ECCEs is used for thesecond EPDCCH, the first set of the numbers of ECCEs includes 2, 4, 8,16, and 32, and the second set of the numbers of ECCEs includes 1, 2, 4,8, and
 16. 4. The terminal device according to claim 1, wherein, in acase that the terminal device detects the first EPDCCH, a physicaldownlink shared channel (PDSCH) scheduled by the first EPDCCH starts inthe first slot, and in a case that the terminal device detects thesecond EPDCCH, a physical downlink shared channel (PDSCH) scheduled bythe second EPDCCH starts in the second slot.
 5. A base station deviceconfigured to communicate with a terminal device (UE), the base stationdevice comprising: a transmission unit configured to transmit multipleenhanced physical downlink control channels (EPDCCHs) on a Secondarycell, wherein, in a case that the Secondary cell is a licensed assistedaccess Secondary cell and a higher layer parameter of the Secondary cellindicates that a starting position of downlink transmission is either aSubframe boundary or a slot boundary, the terminal device is configuredto monitor both a first set of UE-specific search space candidates in afirst EPDCCH and a second set of the UE-specific search space candidatesin a second EPDCCH, in a subframe, a starting symbol for the firstEPDCCH is given by an index in a first slot in the subframe, and astarting symbol for the second EPDCCH is given by the index in a secondslot in the subframe.
 6. The base station device according to claim 5,wherein a demodulation reference signal (DMRS) associated with the firstEPDCCH is transmitted in both the first slot and the second slot, and aDMRS associated with the second EPDCCH is transmitted only in the secondslot.
 7. The base station device according to claim 5, wherein a firstset of numbers of enhanced control channel elements (ECCEs) or a secondset of numbers of ECCEs is used for the first EPDCCH, only the first setof the numbers of ECCEs is used for the second EPDCCH, the first set ofthe numbers of ECCEs includes 2, 4, 8, 16, and 32, and the second set ofthe numbers of ECCEs includes 1, 2, 4, 8, and
 16. 8. The base stationdevice according to claim 5, wherein, in a case that the terminal devicedetects the first EPDCCH, a physical downlink shared channel (PDSCH)scheduled by the first EPDCCH starts in the first slot, and in a casethat the terminal device detects the second EPDCCH, a physical downlinkshared channel (PDSCH) scheduled by the second EPDCCH starts in thesecond slot.
 9. A communication method of a terminal device (UE), thecommunication method comprising the step of: monitoring, by the terminaldevice, multiple enhanced physical downlink control channels (EPDCCHs)on a Secondary cell, wherein in a case that the Secondary cell is alicensed assisted access Secondary cell and a higher layer parameter ofthe Secondary cell indicates that a starting position of downlinktransmission is either a Subframe boundary or a slot boundary, theterminal device is configured to monitor both a first set of UE-specificsearch space candidates in a first EPDCCH and a second set of theUE-specific search space candidates in a second EPDCCH, in a subframe, astarting symbol for the first EPDCCH is specified by an index in a firstslot in the subframe, and a starting symbol for the second EPDCCH isspecified by the index in a second slot in the subframe.
 10. Acommunication method of a base station device configured to communicatewith a terminal device (UE), the communication method comprising thestep of: transmitting, by the base station device, multiple enhancedphysical downlink control channels (EPDCCHs) on a Secondary cell,wherein in a case that the Secondary cell is a licensed assisted accessSecondary cell and a higher layer parameter of the Secondary cellindicates that a starting position of downlink transmission is either aSubframe boundary or a slot boundary, the terminal device is configuredto monitor both a first set of UE-specific search space candidates in afirst EPDCCH and a second set of the UE-specific search space candidatesin a second EPDCCH, in a subframe, a starting symbol for the firstEPDCCH is specified by an index in a first slot in the subframe, and astarting symbol for the second EPDCCH is specified by the index in asecond slot in the subframe.